# new to keeping predatory beetles - what to feed Calosoma scrutator



## ErinM31 (Apr 20, 2016)

By fortune I found a _Calosoma scrutator_ yesterday evening. It's a bit smelly, yes, but truly a gorgeous beetle with its copper trim and as others have mentioned, it's underside is psychedelic. I would like to keep it, but only if I don't have to hunt down caterpillars! I did some searching on the forum about predatory beetles and that people have had success feeding their _Pasimachus_ species crickets, even though BugGuide lists them as eating caterpillars and other larva in the wild.

I found several threads offering the "fiery searcher," _Calosoma scrutator_, for sale, but not instructions on their keeping. Has anyone successful kept, fed, even bred these beetles? And how about _Pasimachus_? I couldn't find care sheets for either genus, not that those are the best sources but would be a start until I could find better advice here.

The only beetles I've kept before are feeders -- bean beetles and mealworms -- and as I once said, I can hardly take any credit for success in that; it's more like containing an infestation. 













Calosoma scrutator



__ ErinM31
__ Apr 20, 2016
__
beetle
metallic




						I found this stunning beetle outside a Walgreens last night. I would like to keep it, if I can...


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## Hisserdude (Apr 20, 2016)

ErinM31 said:


> By fortune I found a _Calosoma scrutator_ yesterday evening. It's a bit smelly, yes, but truly a gorgeous beetle with its copper trim and as others have mentioned, it's underside is psychedelic. I would like to keep it, but only if I don't have to hunt down caterpillars! I did some searching on the forum about predatory beetles and that people have had success feeding their _Pasimachus_ species crickets, even though BugGuide lists them as eating caterpillars and other larva in the wild.
> 
> I found several threads offering the "fiery searcher," _Calosoma scrutator_, for sale, but not instructions on their keeping. Has anyone successful kept, fed, even bred these beetles? And how about _Pasimachus_? I couldn't find care sheets for either genus, not that those are the best sources but would be a start until I could find better advice here.
> 
> ...


Many people have kept Calosoma, and they will eat crickets and other soft bodied invertebrates in captivity, along with some processed animal foods like fish pellets, dog food, etc. They can live for up to two years in captivity, and are pretty hardy. The hard part about keeping ground beetles is breeding them, few have done it successfully. @Elytra and Antenna has bred Calosoma in the past, but the larva were weak and the impetus for oviposition remains unknown.

Reactions: Agree 1 | Helpful 1


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## Hisserdude (Apr 20, 2016)

Oh, and Pasimachus are also hardy in captivity and will readily eat anything you put their enclosures. Breeding these is extremely hard, I only know of one person that got his to lay an egg and the resulting larva died for seemingly no reason before it got a chance to mature.

Reactions: Agree 1 | Informative 1


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## ErinM31 (Apr 20, 2016)

Good to know! Thank you! 
Any recommendations on substrate? Would dry peat, coco fiber, and/or topsoil would work? Or do they prefer some moisture? I'm guessing that most would work for keeping adults and specific requirements would only be for oviposition and larva.


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## Tenevanica (Apr 20, 2016)

ErinM31 said:


> Good to know! Thank you!
> Any recommendations on substrate? Would dry peat, coco fiber, and/or topsoil would work? Or do they prefer some moisture? I'm guessing that most would work for keeping adults and specific requirements would only be for oviposition and larva.


I use coco peat, but I'm sure Hisserdude has some other substrate concoction that works better.

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## ErinM31 (Apr 20, 2016)

Thank you both! Somehow I found the thread on here on _Pasimachus_ larvae (that turned out to be _Calosoma scrutator_) through Google instead of my search here -- go figure, lol. It looked like they used a sort of moist composite (they started out trying to raisw millipedes... hmm, notice a theme there? Lol) I have half a mind to freeze or bake (or both) some composite of dirt and leaves from the outdoors since they're native. Speaking of which, while searching for millipedes, I come across LOTS of gray grubs... but they're probably not anything interesting, nothing predatory at least, probably one if the numerous scarab/may/june beetles around here.


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## ErinM31 (Apr 20, 2016)

I took a look on BugGuide -- wow but Pasimachus larva are ugly!  They look like a centipede with too few legs and is very angry about the situation (sorry, but centipedes still give me the creeps). But then I guess it would be more of a surprise if the offspring of this warrior tank were cute, lol.


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## BobBarley (Apr 20, 2016)

ErinM31 said:


> I took a look on BugGuide -- wow but Pasimachus larva are ugly!  They look like a centipede with too few legs and is very angry about the situation (sorry, but centipedes still give me the creeps). But then I guess it would be more of a surprise if the offspring of this warrior tank were cute, lol.


I just got two Pasmiachus viridans (adults of course) and they are absolutely gorgeous!


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## Hisserdude (Apr 20, 2016)

ErinM31 said:


> Good to know! Thank you!
> Any recommendations on substrate? Would dry peat, coco fiber, and/or topsoil would work? Or do they prefer some moisture? I'm guessing that most would work for keeping adults and specific requirements would only be for oviposition and larva.


I use coconut fiber for most of my Carabids, but a mix of unfertilized potting soil, coconut fiber and some rotten wood may help to induce egg laying. A layer of dead leaves neber hurts either. 

Orin had a clean-up crew of isopods when his laid eggs, so they may help induce the beetles to oviposit.

Reactions: Helpful 1


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## Hisserdude (Apr 20, 2016)

ErinM31 said:


> I took a look on BugGuide -- wow but Pasimachus larva are ugly!  They look like a centipede with too few legs and is very angry about the situation (sorry, but centipedes still give me the creeps). But then I guess it would be more of a surprise if the offspring of this warrior tank were cute, lol.


Hey, those larva look freaking awesome! Then again, things like that and centipedes don't creep me out.

Reactions: Agree 1


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## Sarkhan42 (Apr 20, 2016)

Just got 3 pasimachus (I believe californicus), and this thread reminded me to ask, how large of an enclosure are these kinds of beetles usually kept in? I've been using pretty deep sub, and they have been readily burrowing often, but wasn't sure what length and width I should be looking at.

Edit: forgot to mention I'm not keeping them communal, not willing to take the risk!


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## pannaking22 (Apr 20, 2016)

I've kept various large carabids a couple times and they do just fine on cocofiber with a moisture gradient and a few hides. Toss in something soft for them to much on once or twice a week. I personally keep mine in medium critter keepers or those flip top boxes from Walmart - http://www.walmart.com/ip/44785855?...9556352&wl4=&wl5=pla&wl6=130447929872&veh=sem

_Pasimachus, Calosoma,_ and _Carabus_ can all be kept this way. Hardy little guys and quite entertaining once you get back the defensive chemicals.

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## Hisserdude (Apr 20, 2016)

Here are a few interesting threads about rearing Carabids, especially Calosoma.

http://arachnoboards.com/threads/beetle-larvae-id-anybody.166024/

http://beetleforum.net/forums/index.php?showtopic=663

http://www.roachforum.com/index.php?showtopic=5244

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## Sarkhan42 (Apr 21, 2016)

Thoughts on a 60/40 or so soil to sand mixture for the pasimachus? Tried it out and it seems to be working well, it holds tunnel shape quite nicely.

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## Hisserdude (Apr 21, 2016)

Sarkhan42 said:


> Thoughts on a 60/40 or so soil to sand mixture for the pasimachus? Tried it out and it seems to be working well, it holds tunnel shape quite nicely.


Yes that sounds like a good substrate for them, may even induce oviposition.

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## Sarkhan42 (Apr 21, 2016)

Hisserdude said:


> Yes that sounds like a good substrate for them, may even induce oviposition.


A goal of mine eventually! Someone just has to figure out how to get these guys reproducing, they're way to cool not to get more common in the hobby.

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## Hisserdude (Apr 21, 2016)

Sarkhan42 said:


> A goal of mine eventually! Someone just has to figure out how to get these guys reproducing, they're way to cool not to get more common in the hobby.


I agree, someone needs ro figure out a repeatable method of breeding these in captivity. Getting them to mate is easy, but getting them to lay eggs is pretty hard, and for some reason ground beetle larva are prone to unusual die offs.


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> I use coconut fiber for most of my Carabids, but a mix of unfertilized potting soil, coconut fiber and some rotten wood may help to induce egg laying. A layer of dead leaves neber hurts either.
> 
> Orin had a clean-up crew of isopods when his laid eggs, so they may help induce the beetles to oviposit.


Good to know! At present, my _Calosoma_ has a gradient from a mix of dry peat, coco fiber and sand to moist peat and sphagnum moss. I put his bark hide on the dry side and he clearly likes the dead leaves as he felt it necessary to extend them out to the feeding dish before retrieving the pre-killed cricket I left for him last night. If I can find another and determine genders, I'll transfer to a larger enclosure with wood and isopods too. I should determine the gender as the _Calosoma_ is one of the few of my non-feline pets to have a name, "His Majesty" 

@pannaking22 and @Hisserdude thank you both for the advice and links!

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## ErinM31 (Apr 21, 2016)

My _Pasimachus_ (only keeping those temporarily) would probably prefer more substrate to burrow in but a layer of dead oak leaves seems to be satisfactory for now. Unless the cricket I gave it happened to keel over last night, the _Pasimachus_ with sufficient leaf cover hunted it down where as the other was still running around so I gave it more leaves and pre-killed its cricket -- this time, lol. Hey, I see links to YouTube videos saying they take down scorpions and the like so I expect them to take down their own crickets!

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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> Good to know! At present, my _Calosoma_ has a gradient from a mix of dry peat, coco fiber and sand to moist peat and sphagnum moss. I put his bark hide on the dry side and he clearly likes the dead leaves as he felt it necessary to extend them out to the feeding dish before retrieving the pre-killed cricket I left for him last night. If I can find another and determine genders, I'll transfer to a larger enclosure with wood and isopods too. I should determine the gender as the _Calosoma_ is one of the few of my non-feline pets to have a name, "His Majesty"
> 
> @pannaking22 and @Hisserdude thank you both for the advice and links!


Nice, sounds like a great substrate mix, hopefully you got a pair there! Let us know how they do! 



ErinM31 said:


> My _Pasimachus_ (only keeping those temporarily) would probably prefer more substrate to burrow in but a layer of dead oak leaves seems to be satisfactory for now. Unless the cricket I gave it happened to keel over last night, the _Pasimachus_ with sufficient leaf cover hunted it down where as the other was still running around so I gave it more leaves and pre-killed its cricket -- this time, lol. Hey, I see links to YouTube videos saying they take down scorpions and the like so I expect them to take down their own crickets!


If you're only keeping them temporarily, then when you want to get rid of them you should sell them. They are in high demand, heck I would buy them from you if I weren't saving up my money for roaches!

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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> Nice, sounds like a great substrate mix, hopefully you got a pair there! Let us know how they do!


Thank you and will do! 



Hisserdude said:


> If you're only keeping them temporarily, then when you want to get rid of them you should sell them. They are in high demand, heck I would buy them from you if I weren't saving up my money for roaches!


Yep, I'm collecting them for Peter of BugsInCyberspace so I'm trying to find the right balance to keep the beetles happy and healthy until I have enough to ship but not have beetle enclosures take over my whole apartment! 

There are a lot of _Pasimachus_ beetles around here -- maybe I could trade you a few for some local millipedes?

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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> There are a lot of _Pasimachus_ beetles around here -- maybe I could trade you a few for some local millipedes?


I'm afraid you'd be very disappointed, the only millipedes I've seen here are the invasive Polydesmus and tiny Julida sp, as well as the occasional Polyxenus sp. Most of the habitat here is dry scrub, but the few forests I've been to have only had tiny Julida species.


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> I'm afraid you'd be very disappointed, the only millipedes I've seen here are the invasive Polydesmus and tiny Julida sp, as well as the occasional Polyxenus sp. Most of the habitat here is dry scrub, but the few forests I've been to have only had tiny Julida species.


I was not aware that we had invasive Polydesmids too. Out of curiosity, do you know what the species is/are?

Who do you buy your roaches from?


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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> I was not aware that we had invasive Polydesmids too. Out of curiosity, do you know what the species is/are?
> 
> Who do you buy your roaches from?


Yeah, the invasive European Polydesmus is common in backyards across America, it has yet to be identified down to species though. There are a few invasive Julids too, Blaniulus guttulatus and a Brachyiulus species for example.

I get my roaches from a lot of different places, Roach crossing.com, Bugsincyberspace, I have bought and traded with several people on the Allpet roaches forum.


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> Yeah, the invasive European Polydesmus is common in backyards across America, it has yet to be identified down to species though. There are a few invasive Julids too, Blaniulus guttulatus and a Brachyiulus species for example.


May I see a picture then? Come to think of it, if I'm putting something together on identifying millipedes in North America, I should include invasive species too, even if the focus is on the natives.



Hisserdude said:


> I get my roaches from a lot of different places, Roach crossing.com, Bugsincyberspace, I have bought and traded with several people on the Allpet roaches forum.


Since you've always been so helpful, I was thinking of offering to send you some at shipping cost, but that itself may be expensive, especially depending on weather. So I was thinking, if you buy from BugsInCyberspace, I might include a few extra Pasimachus once I find enough to ship with the request that he include a few with your roach purchase. Maybe I am thinking too far ahead with too many variables... that is me! Lol. First things first, I need to find more of them...


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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> May I see a picture then? Come to think of it, if I'm putting something together on identifying millipedes in North America, I should include invasive species too, even if the focus is on the natives.
> 
> Since you've always been so helpful, I was thinking of offering to send you some at shipping cost, but that itself may be expensive, especially depending on weather. So I was thinking, if you buy from BugsInCyberspace, I might include a few extra Pasimachus once I find enough to ship with the request that he include a few with your roach purchase. Maybe I am thinking too far ahead with too many variables... that is me! Lol. First things first, I need to find more of them...


Sure, I got pics of the Polydesmus, but I haven't got any pics of the Juids, mainly because they are so tiny.













I can try to get some pictures of the Julids, if I can find any...

That's really nice of you, I would be more than willing to pay for the shipping if you can find some extra beetles, it should only be around $7-8 dollars if you are using USPS 2 day Priority, which would be fine for these guys.  Any pics of the Pasimachus?


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> Sure, I got pics of the Polydesmus, but I haven't got any pics of the Juids, mainly because they are so tiny.
> 
> 
> 
> ...


Oh, that's fine; I was mostly curious what the invasive _Polydesmids_ looked like. Even if the species is not known, someone must have recognized them as endogenous to somewhere else. They must have some name, even if science hasn't decided how to classify them yet. Do you know where they come from? I am just curious and some of this info I would like to include in my project. I do not want any as I am focusing on the natives, which are prettier anyway, plus it would probably be frowned upon, if not illegal, to spread an invasive species. Thank you for the pics and info would be great too, if you know any of it. BugGuide has become my go-to source but they focus on species native to the Americas as well.

I'll try to take some pics of the _Pasimachus_ beetles when I get home tonight -- not easy since they're liable to race about if I get one out of hiding. Maybe I can be sneaky... or fortunate... hehe. Okay, I wasn't sure what kind of shipping they would require and what the temperatures will be here and there. I have never shipped any creature before, nor have I bought any beetles. The most common way that I have received tarantulas, millipedes, and isopods is in an aerated deli cup of the appropriate size with damp cloth or paper towel. The _E. murinus_ slings I bought from @JohnDapiaoen were each carefully wrapped in it's own vial so there was no chance of justling about and getting injured (plus I imagine they felt snug inside a burrow for their journey) but HOW he managed to get these slings, which have the ability to teleport  to be still for such a process is a mystery to me. Do you know what the best way (or what good ways there are) to package these beetles for shipping?


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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> Oh, that's fine; I was mostly curious what the invasive _Polydesmids_ looked like. Even if the species is not known, someone must have recognized them as endogenous to somewhere else. They must have some name, even if science hasn't decided how to classify them yet. Do you know where they come from? I am just curious and some of this info I would like to include in my project. I do not want any as I am focusing on the natives, which are prettier anyway, plus it would probably be frowned upon, if not illegal, to spread an invasive species. Thank you for the pics and info would be great too, if you know any of it. BugGuide has become my go-to source but they focus on species native to the Americas as well.
> 
> I'll try to take some pics of the _Pasimachus_ beetles when I get home tonight -- not easy since they're liable to race about if I get one out of hiding. Maybe I can be sneaky... or fortunate... hehe. Okay, I wasn't sure what kind of shipping they would require and what the temperatures will be here and there. I have never shipped any creature before, nor have I bought any beetles. The most common way that I have received tarantulas, millipedes, and isopods is in an aerated deli cup of the appropriate size with damp cloth or paper towel. The _E. murinus_ slings I bought from @JohnDapiaoen were each carefully wrapped in it's own vial so there was no chance of justling about and getting injured (plus I imagine they felt snug inside a burrow for their journey) but HOW he managed to get these slings, which have the ability to teleport  to be still for such a process is a mystery to me. Do you know what the best way (or what good ways there are) to package these beetles for shipping?


They are from Europe, just like most of the isopods in people's backyards. Those are legal to ship around, so I doubt there are regulations on these millipedes. Many common backyard inverts are from Europe, these millipedes, the common stone centipedes, isopods, a few rove beetle species, and some others that I can't think of right now. Here is the link to the Polydesmus page on bugguide: http://bugguide.net/node/view/97396 Bugguide will focus on any bug in NA, native or invasive, after all someone has to keep track of what new species are being introduced here.

Cool, you can try putting them in the fridge for a few minutes to slow them down, they hibernate in nature anyway, so it shouldn't harm them. Yes, a deli cup with moist paper towel in it is what I would ship them in, it's what I ship everything in. I imagine they would be easier to get in the cup than a teleporting sling, lol!


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> They are from Europe, just like most of the isopods in people's backyards. Those are legal to ship around, so I doubt there are regulations on these millipedes. Many common backyard inverts are from Europe, these millipedes, the common stone centipedes, isopods, a few rove beetle species, and some others that I can't think of right now.


Oh that's true and I imagine they're probably as harmless as most of those... At least I like our imported isopods, hehe. I remember some years ago there were some other beetles -- from Asia I think -- that were highly damaging to trees here and they were trying to stop the spread and then there are regulations concerning bean beetles which are crop pests. But that's a different sort of thing entirely. As you said, isopods are commonly shipped (and already everywhere they can survive) and so are the non-native bumblebee and scarlet millipedes that weren't native but can now be found in the wild (I think).

Well, I shall still let you keep them, thank you. 



Hisserdude said:


> Here is the link to the Polydesmus page on bugguide: http://bugguide.net/node/view/97396 Bugguide will focus on any bug in NA, native or invasive, after all someone has to keep track of what new species are being introduced here.


Oh, I did not know that! When browsing BugGuide earlier, it looked to me like families/genera/whatever were left out if they weren't native, but maybe it's only if they aren't found here or the groups were missing for some other reason. But you're absolutely right and it makes sense for them to be included -- thank you for the link! 



Hisserdude said:


> Cool, you can try putting them in the fridge for a few minutes to slow them down, they hibernate in nature anyway, so it shouldn't harm them. Yes, a deli cup with moist paper towel in it is what I would ship them in, it's what I ship everything in. I imagine they would be easier to get in the cup than a teleporting sling, lol!


Okay, sounds good.  I thought cold might be the trick. It takes a while for a container of bean beetles to get slowed down whereas the black _Calosoma_ was out so fast and on it's back, I feared I'd killed it! It took a while to slowly come to but hopefully suffered no ill effects. I shall be careful with the _Pasimachus_.


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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> Oh that's true and I imagine they're probably as harmless as most of those... At least I like our imported isopods, hehe. I remember some years ago there were some other beetles -- from Asia I think -- that were highly damaging to trees here and they were trying to stop the spread and then there are regulations concerning bean beetles which are crop pests. But that's a different sort of thing entirely. As you said, isopods are commonly shipped (and already everywhere they can survive) and so are the non-native bumblebee and scarlet millipedes that weren't native but can now be found in the wild (I think).
> 
> Well, I shall still let you keep them, thank you.
> 
> ...


They probably make just as much of an impact in the wild as isopods do, which is not much. And they have already become naturalized across NA, so shipping them around probably wouldn't make any impact to their population.

Yeah they are pretty dull for a millipede, and they are small. I'll probably try to breed them anyway, seeing as I don't have many other millipedes to choose from here, lol!  

Yeah Bugguide has everything, it is a truly amazing website! 

Cool, hope you can get some good pics! Be careful and just make sure you don't leave it in too long, or else you'll end up with a beetlecicle, lol!


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## ErinM31 (Apr 21, 2016)

Wow, I thought "His Majesty" was happy but no, NO, not at all! He wants to go hunting or mating or something. Anyway, he's pacing about his enclosure then will stop and make a sound like a buzzsaw and then try to take off -- I had no idea these beetles could fly! This beetle will definitely require a larger enclosure than the small critter keeper I had available. I don't know what size would be enough and if I have room for that what with amphibians and tarantulas and millipedes... It's a really beautiful beetle but perhaps needs more than I can provide.

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## Hisserdude (Apr 21, 2016)

Eh, many inverts will try to fly every now and then, he should be fine in a shoe box or something similar. You shouldn't need a tank or anything like that. How many inches of substrate does it have?


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## ErinM31 (Apr 21, 2016)

Hisserdude said:


> They probably make just as much of an impact in the wild as isopods do, which is not much. And they have already become naturalized across NA, so shipping them around probably wouldn't make any impact to their population.
> 
> Yeah they are pretty dull for a millipede, and they are small. I'll probably try to breed them anyway, seeing as I don't have many other millipedes to choose from here, lol!


Lol, maybe they'll have some interesting behaviors and I'd imagine they'd be easy to keep and breed, seeing as how they've spread. And maybe they fluoresce under blacklight like other _Polydesmids_ which looks really cool. 



Hisserdude said:


> Yeah Bugguide has everything, it is a truly amazing website!


Agreed! 



Hisserdude said:


> Cool, hope you can get some good pics! Be careful and just make sure you don't leave it in too long, or else you'll end up with a beetlecicle, lol!


I took some photos of the feistier one.  My iPhone has issues with reflectivity and was always focusing on the substrate, grrr. The white rocks are just something I had in a box and thought the beetle would look well against.

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## BobBarley (Apr 21, 2016)

ErinM31 said:


> Lol, maybe they'll have some interesting behaviors and I'd imagine they'd be easy to keep and breed, seeing as how they've spread. And maybe they fluoresce under blacklight like other _Polydesmids_ which looks really cool.
> 
> 
> 
> ...


Interesting ridges on the elytra.  Do all the specimens have those ridges?


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## Hisserdude (Apr 21, 2016)

ErinM31 said:


> Lol, maybe they'll have some interesting behaviors and I'd imagine they'd be easy to keep and breed, seeing as how they've spread. And maybe they fluoresce under blacklight like other _Polydesmids_ which looks really cool.
> 
> 
> 
> ...


Yeah, they probably don't even need rotten wood in their diet, seeing as I find them in my backyard and there are not many dead trees here at all.

Nice, seems like P.californicus, though it could be depressus. I can't tell from these pics, are the margins purple or just black? Either way they are beautiful beetles, would love to own some! (And try to breed them).  I wonder what exactly is needed for oviposition, and how this guy was able to do it? http://beetleforum.net/forums/index.php?showtopic=1708&hl=pasimachus


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## BobBarley (Apr 21, 2016)

Hisserdude said:


> Nice, seems like P.californicus, though it could be depressus. I can't tell from these pics, are the margins purple or just black? Either way they are beautiful beetles, would love to own some! (And try to breed them).  I wonder what exactly is needed for oviposition, and how this guy was able to do it? http://beetleforum.net/forums/index.php?showtopic=1708&hl=pasimachus


Do you find the indentations going down the elytra to be significant?


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## Jacob Ma (Apr 22, 2016)

You lucky duck!  The only beetle that looks remotely close to & is common in my area is _Scarites subterraneus_, but they are a lot smaller than _Pasimachus sp._
I recently found a single, but decently sized _Narceus americanus_ (American millipede) under a log, and is there anything I can trade for that?  It is a red and grey striped millipede currently around 9-10 cms.  I can try to make an effort to find some more later this spring or summer.


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## Hisserdude (Apr 22, 2016)

BobBarley said:


> Do you find the indentations going down the elytra to be significant?


Those indentations are probably due to poor pupation conditions, and must have been obtained when the beetle was still teneral. Those indentations are not natural.


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## Hisserdude (Apr 22, 2016)

Jacob Ma said:


> You lucky duck!  The only beetle that looks remotely close to & is common in my area is _Scarites subterraneus_, but they are a lot smaller than _Pasimachus sp._
> I recently found a single, but decently sized _Narceus americanus_ (American millipede) under a log, and is there anything I can trade for that?  It is a red and grey striped millipede currently around 9-10 cms.  I can try to make an effort to find some more later this spring or summer.


Scarites and Pasimachus are actually closely related, they are in the same subfamily!  And hey, at least you got Scarites, all we got here is Clivina, which is way smaller than Scarites.


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## BobBarley (Apr 22, 2016)

Hisserdude said:


> Those indentations are probably due to poor pupation conditions, and must have been obtained when the beetle was still teneral. Those indentations are not natural.


I see, though in a pm (conversation I guess) @ErinM31 observed that all the specimens he collected have those indentations.

Edit: I should probably word that better, he believes all the specimens around his area have them.

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## ErinM31 (Apr 22, 2016)

Hisserdude said:


> Eh, many inverts will try to fly every now and then, he should be fine in a shoe box or something similar. You shouldn't need a tank or anything like that. How many inches of substrate does it have?


I'd be afraid to put His Majesty in something like a shoebox now -- I might open it only to have him fly away!  I know the mini Critter Keeper I have him in now is too small but it is only temporary until I figure out whether I'm going to keep and even try to breed _Calosoma_ or sell him or release him. There is only an inch of substrate -- I didn't expect an arboreal hunter of caterpillars to want to burrow. Normally I do research these things more first, only I've been so busy and His Majesty was an unexpected find.



BobBarley said:


> Interesting ridges on the elytra.  Do all the specimens have those ridges?


No, I looked again at both of the _Pasimachus_ specimens that I currently have: In most ways they look the same -- large and black, no other coloring, and same shape of thorax, but only the one I photographed has indentations down the middle of the elytra while the other is smooth. I don't know whether that's a clue to species or gender or if they are battle scars.



Hisserdude said:


> Those indentations are probably due to poor pupation conditions, and must have been obtained when the beetle was still teneral. Those indentations are not natural.


Ahh, thank you for that info. Well, for what little a newbie's opinion is worth, the one with indentations seems otherwise healthy and has lots of attitude!



BobBarley said:


> I see, though in a pm (conversation I guess) @ErinM31 observed that all the specimens he collected have those indentations.
> 
> Edit: I should probably word that better, he believes all the specimens around his area have them.


You could word it better still.  SHE believed that all specimens in her area looked about the same -- which they do superficially, nothing like the difference between the black _Calosoma_ that I found and His Majesty, the green and copper "fiery searcher." However, when you asked about the elytra, I checked the _Pasimachus_ beetles again. (The more you work with a species, the more you notice the differences and know which are important. Until this week, these were just "those large black tank beetles with pincers.") So let me rephrase that to "they all look the same to someone who is not a beetle aficionado". If you ask more specific questions such as about the elytra, I will gladly check for you, so long as it doesn't cost me a finger.

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## Hisserdude (Apr 22, 2016)

BobBarley said:


> I see, though in a pm (conversation I guess) @ErinM31 observed that all the specimens he collected have those indentations.
> 
> Edit: I should probably word that better, he believes all the specimens around his area have them.


Interesting, I still think it they are unnatural, as most of the pictures on Bugguide lack these indentations. Slightly deformed elytra are common in many beetles, I'd say 40% of the Eleodes I find here have at least one minor dent in their elytra. Many of them also have dents in their pronotum as well. I'm sure slightly deformed Pasimachus are common, if not more common than unblemished individuals!


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## ErinM31 (Apr 22, 2016)

Jacob Ma said:


> You lucky duck!  The only beetle that looks remotely close to & is common in my area is _Scarites subterraneus_, but they are a lot smaller than _Pasimachus sp._
> I recently found a single, but decently sized _Narceus americanus_ (American millipede) under a log, and is there anything I can trade for that?  It is a red and grey striped millipede currently around 9-10 cms.  I can try to make an effort to find some more later this spring or summer.


Yes, _Narceus americanus_ is one of the millipede species that I do not yet have and would like.  May I ask what area of the country you live in? There are a few millipede species that I would like that are only in limited areas, such as the Appalachians.


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## Hisserdude (Apr 22, 2016)

ErinM31 said:


> I'd be afraid to put His Majesty in something like a shoebox now -- I might open it only to have him fly away!  I know the mini Critter Keeper I have him in now is too small but it is only temporary until I figure out whether I'm going to keep and even try to breed the _Calosoma_ or sell him or release him. There is only an inch of substrate -- I didn't expect an arboreal hunter of caterpillars to want to burrow. Normally I do research these things more first, only I've been so busy and His Majesty was an unexpected find.
> 
> 
> 
> ...


Eh, he probably won't attempt to fly if you are checking up on him, he's more likely to hide under something. Yes I believe they like to burrow a bit, most Carabids do. 

Small deformities like slight indentations in the elytra don't seem to affect the overall health or lifespan of the beetle at all, and add character.  

As long as you hold them by the sides they shouldn't bite you, and personally I'd be more afraid of their chemical defense fluids than their bite, lol!  Carabids can really stink! (I mean that literally, not metaphorically, Carabids are awesome!).


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## ErinM31 (Apr 22, 2016)

Hisserdude said:


> Eh, he probably won't attempt to fly if you are checking up on him, he's more likely to hide under something. Yes I believe they like to burrow a bit, most Carabids do.


I'm also considering the half-gallon jars that I got -- it would allow for a good amount of substrate and the inclusion of isopods and even a small plant or so. Total surface area should be at least twice what he has now and there would be more room for both climbing and burrowing. Does that sound adequate for two of these (trying to find how to sex them so I can look for one of the opposite gender -- if I decide to go down that route.



Hisserdude said:


> Small deformities like slight indentations in the elytra don't seem to affect the overall health or lifespan of the beetle at all, and add character.


Like diamonds! 



Hisserdude said:


> As long as you hold them by the sides they shouldn't bite you, and personally I'd be more afraid of their chemical defense fluids than their bite, lol!  Carabids can really stink! (I mean that literally, not metaphorically, Carabids are awesome!).


Good to know! Yes, I did notice that the Carabids stank a bit. Fortunately, I managed to not get sprayed by either!

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## Hisserdude (Apr 22, 2016)

ErinM31 said:


> I'm also considering the half-gallon jars that I got -- it would allow for a good amount of substrate and the inclusion of isopods and even a small plant or so. Total surface area should be at least twice what he has now and there would be more room for both climbing and burrowing. Does that sound adequate for two of these (trying to find how to sex them so I can look for one of the opposite gender -- if I decide to go down that route.
> 
> 
> 
> ...


Will these jars have any ventilation in it? If so then the sound like a nice cage choice, and you may be able to keep a pair together so long as you keep them well fed and give them lots of hiding places, including a deepish substrate. 

Even better IMO! 

Good, make sure that stuff never gets in your eyes, I got some Callisthenes defensive fluids in my eyes, and WOW did it sting! Still, I'd rather get that stuff in my eyes than soap or shampoo!


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## BobBarley (Apr 22, 2016)

ErinM31 said:


> You could word it better still.  SHE believed that all specimens in her area looked about the same


Oops! Lol



ErinM31 said:


> (trying to find how to sex them so I can look for one of the opposite gender -- if I decide to go down that route.


Some species of Pasimachus (not sure which ones and not sure if it is a rule for all Pasimachus...) but I've read that the males have more glossy elytra while the females have a more dull elytra.


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## Jacob Ma (Apr 22, 2016)

ErinM31 said:


> Yes, _Narceus americanus_ is one of the millipede species that I do not yet have and would like.  May I ask what area of the country you live in? There are a few millipede species that I would like that are only in limited areas, such as the Appalachians.


I live in Virginia, but the Appalachians are about 2-3 hours away from me since I live closer to the coast.  What species are you interested in?  I can try and keep a tab next time I go someplace over there.


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## ErinM31 (Apr 22, 2016)

Hisserdude said:


> Will these jars have any ventilation in it? If so then the sound like a nice cage choice, and you may be able to keep a pair together so long as you keep them well fed and give them lots of hiding places, including a deepish substrate.
> 
> Even better IMO!
> 
> Good, make sure that stuff never gets in your eyes, I got some Callisthenes defensive fluids in my eyes, and WOW did it sting! Still, I'd rather get that stuff in my eyes than soap or shampoo!


In the lid, yes -- will that be adequate ventilation? They are wide(4")-mouth jars.

@Hisserdude Can you tell me how to distinguish genders in both _Pasimachus_ and _Calisoma scrutator_ beetles, please? I would assume the _Pasimachus_ is either the _depressus_ or _californicus_ species based on range. Your reward shall be the _Pasimachus_ pictured above plus another of the opposite gender at shipping.

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## Hisserdude (Apr 22, 2016)

ErinM31 said:


> In the lid, yes -- will that be adequate ventilation? They are wide(4")-mouth jars.
> 
> @Hisserdude Can you tell me how to distinguish genders in both _Pasimachus_ and _Calisoma scrutator_ beetles, please? I would assume the _Pasimachus_ is either the _depressus_ or _californicus_ species based on range. Your reward shall be the _Pasimachus_ pictured above plus another of the opposite gender at shipping.


Yeah as long as there are some holes in the lid that should be good.

Well unfortunately there is no clear or easy way to definitively identify genders in ground beetles, their undersides look the same and the males don't have horns. In general the males are smaller than the females, sometimes by half as much. Sometimes it's not so easy to see the difference in size though, size can vary by how much food they got as a larva, so you can find small females and large males.
This is an image of a mating pair of C.scrutator:





As you can see here, the male is not too much smaller than the female, and if they weren't mating it would be hard to tell the difference. If you put two individuals together and they mate, then they are probably a male and a female. However, to confuse things further, males can be desperate to mate and will sometimes try to mate with another male...

So to recap things:
The best way to tell the sexes apart is by size, males will probably be 3/4 the size of the females, though size can vary greatly in WC adults.
Seeing if two individuals will mate is not enough to tell genders apart, as males will sometimes try to mate with any gender beetle.

Unfortunately neither of these beetle species have any sort of noticeable sexual dimorphism, so all you can really do is guess... Still sometimes it is quite apparent what sex is which when using size. So, did I win, or did the lack of a useful answer disqualify me?

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## ErinM31 (Apr 23, 2016)

Hisserdude said:


> Yeah as long as there are some holes in the lid that should be good.
> 
> Well unfortunately there is no clear or easy way to definitively identify genders in ground beetles, their undersides look the same and the males don't have horns. In general the males are smaller than the females, sometimes by half as much. Sometimes it's not so easy to see the difference in size though, size can vary by how much food they got as a larva, so you can find small females and large males.
> This is an image of a mating pair of C.scrutator:
> ...


Lol, I was already going to send you the beetles for all the help you have been!  I suppose winning is if I am able to guess the genders right and send you a pair.  I think the two Pasimachus that I have now are females or well-fed males -- or there are some truly monstrously sized beetles that I have yet to find!

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## Hisserdude (Apr 23, 2016)

ErinM31 said:


> Lol, I was already going to send you the beetles for all the help you have been!  I suppose winning is if I am able to guess the genders right and send you a pair.  I think the two Pasimachus that I have now are females or well-fed males -- or there are some truly monstrously sized beetles that I have yet to find!


Haha thanks, was worried for a bit there!  Even two females would be fine, as chances are they have already been mated. No it's two males that you would need to worry about, ain't no eggs coming out of those lol!  Even two males would make really cool pets, they are pretty long lived after all!

Yeah if they are both pretty big then they are likely females, or like you said, there are some big girls out there that you haven't seen yet!

PM me whenever you have enough beetles to send to me and BIC, I don't want to poach his beetles lol!


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## Jacob Ma (Apr 23, 2016)

@Hisserdude you don't mind if I steal this, and give you the credit?  XD  This same method goes for most ground beetles from what I have heard.

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## ErinM31 (Apr 23, 2016)

Jacob Ma said:


> I live in Virginia, but the Appalachians are about 2-3 hours away from me since I live closer to the coast.  What species are you interested in?  I can try and keep a tab next time I go someplace over there.


There are several stunning Platydesmids in the area. I'll check BugGuide again and send you a list.


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## Jacob Ma (Apr 23, 2016)

Oh my gosh!  I never knew feather millipedes live not so far from me!  I will be sure to send you some and maybe snag a few myself (if I get any) the next ime I go sometimes this summer.


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## Jacob Ma (Apr 23, 2016)

OK, here it goes: I'll give you all a chance to determine which is the right sex!  The prize is a check(mark)
There are 2 males and one female out of the bunch.  Note that the eye discoloration has nothing to do with gender.


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## BobBarley (Apr 23, 2016)

Jacob Ma said:


> OK, here it goes: I'll give you all a chance to determine which is the right sex!  The prize is a check(mark)
> There are 2 males and one female out of the bunch.  Note that the eye discoloration has nothing to do with gender.


Top 2 are male and bottom is female?  Just taking a crack at it.

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## Hisserdude (Apr 23, 2016)

Jacob Ma said:


> @Hisserdude you don't mind if I steal this, and give you the credit?  XD  This same method goes for most ground beetles from what I have heard.


Not at all lol!


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## Hisserdude (Apr 23, 2016)

Jacob Ma said:


> OK, here it goes: I'll give you all a chance to determine which is the right sex!  The prize is a check(mark)
> There are 2 males and one female out of the bunch.  Note that the eye discoloration has nothing to do with gender.


I agree with @BobBarley on this one, the top two look male to me, and the bottom one looks female.

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## MWAInverts (Apr 23, 2016)

Agreed like the others, top two are males

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## Jacob Ma (Apr 23, 2016)

You guys are right!  It may or may not have been noticed, but if you look at the beetles' pretarsi (front legs, at their feet), the segments in the males are much more squarish than the females triangular/trapezoidal segments.  So it looks like you guys all get credit!

In case you didn't know, the pretarsi on males helps with gripping onto the female during mating.

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## Hisserdude (Apr 23, 2016)

Jacob Ma said:


> You guys are right!  It may or may not have been noticed, but if you look at the beetles' pretarsi (front legs, at their feet), the segments in the males are much more squarish than the females triangular/trapezoidal segments.  So it looks like you guys all get credit!
> 
> In case you didn't know, the pretarsi on males helps with gripping onto the female during mating.


Interesting, thanks for sharing! Looks like there is a reliable way to sex Calosoma after all! Can all ground beetles be sexed this way?


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## ErinM31 (Apr 23, 2016)

Good to know


Jacob Ma said:


> You guys are right!  It may or may not have been noticed, but if you look at the beetles' pretarsi (front legs, at their feet), the segments in the males are much more squarish than the females triangular/trapezoidal segments.  So it looks like you guys all get credit!
> 
> In case you didn't know, the pretarsi on males helps with gripping onto the female during mating.


Good to know -- thank you!  It is similar in some toad species; the males have protrusions on their front digits to help grip the female.

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## MWAInverts (Apr 23, 2016)

In a lot of beetle species the pretarsi segments on males will be highly modified for grasping. I do believe almost 100% of male aquatic beetles have them as well.

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## Jacob Ma (Apr 23, 2016)

They are different in a lot of shelled species, as this adaptation is even evident in tortoises.  However, the pretarsi segments vary in appearance, like for aquatic beetles there is a large suction cup instead of dilated segments to grip to smooth shells in flowing water.  For most ground beetles, this adaptation is featured on them, but as I said it varies in appearance so it may or may not be difficult to tell the sex of a male or female.

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## BobBarley (Apr 30, 2016)

Hisserdude said:


> Interesting, thanks for sharing! Looks like there is a reliable way to sex Calosoma after all! Can all ground beetles be sexed this way?


To me, it the difference looks evident in these to pictures of P. depressus

Male with more roundish segments on their front legs: http://bugguide.net/node/view/371153/bgpage
Female with more triangular segments on their front legs: http://bugguide.net/node/view/520032/bgpage


EDIT: Also, in P. californicus: 
Male: http://bugguide.net/node/view/903980/bgpage
Female: http://bugguide.net/node/view/935302/bgpage

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## Hisserdude (Apr 30, 2016)

BobBarley said:


> To me, it the difference looks evident in these to pictures of P. depressus
> 
> Male with more roundish segments on their front legs: http://bugguide.net/node/view/371153/bgpage
> Female with more triangular segments on their front legs: http://bugguide.net/node/view/520032/bgpage
> ...


Very interesting, thanks for sharing! That picture of the P.californicus male also says: One of the noticeable external features of male P. californicus, shared with male P. punctulatus, is a dense brush of golden setae on the apical third of the hind tibiae.

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## ErinM31 (Apr 30, 2016)

Hisserdude said:


> Very interesting, thanks for sharing! That picture of the P.californicus male also says: One of the noticeable external features of male P. californicus, shared with male P. punctulatus, is a dense brush of golden setae on the apical third of the hind tibiae.


Yeah, it seems it won't be difficult to tell the males and females apart after all.  Also, finding a male will help determine whether I have _P. californicus_ or _P. depressus_ (although I suppose it's entirely possible that both could live around here). Right now, my money is on _P. depressus_.

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## BobBarley (May 3, 2016)

Alright, well if you ever try to sex your live Pasimachus, they _do not_ stay still.  I ended up taking a video and looking through the frames for the one millisecond that my P. viridans stayed still.
	

		
			
		

		
	



	

		
			
		

		
	
 Well, relatively still at least...  Looking male!


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## Hisserdude (May 3, 2016)

BobBarley said:


> Alright, well if you ever try to sex your live Pasimachus, they _do not_ stay still.  I ended up taking a video and looking through the frames for the one millisecond that my P. viridans stayed still.
> 
> 
> 
> ...


Yeah, that's a problem that happens with a lot of bugs, it's hard to take a picture of something when it's running or flying all over the place, especially if you are going for a small portion of the body. 
I agree, looks male!

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## ErinM31 (May 3, 2016)

BobBarley said:


> Alright, well if you ever try to sex your live Pasimachus, they _do not_ stay still.  I ended up taking a video and looking through the frames for the one millisecond that my P. viridans stayed still.
> 
> 
> 
> ...


Nice! You've a good camera to get such focus in close-up. My iPhone doesn't do well on things that small.  I need a camera with a macro lens!

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## BobBarley (May 3, 2016)

ErinM31 said:


> Nice! You've a good camera to get such focus in close-up. My iPhone doesn't do well on things that small.  I need a camera with a macro lens!


Lol I actually use an iPad mini!  I bought a macro lens for $10 on Amazon.


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## ErinM31 (May 3, 2016)

BobBarley said:


> Lol I actually use an iPad mini!  I bought a macro lens for $10 on Amazon.


Oh wow! I thought I was going to have to wait until I could afford an expensive camera -- I had no idea they sold inexpensive macro lens attachments for iPhones -- awesome!

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