new to keeping predatory beetles - what to feed Calosoma scrutator

[ErinM31]

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.

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.

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!

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.

 

[Hisserdude]

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!

 

[ErinM31]

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.

 

[Hisserdude]

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.



No, I looked again at both 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. I don't know whether that's a clue to species or gender or if they are battle scars.



Ahh, thank you for that info. For what little a newbie's opinion is worth, that one seems otherwise in good health and is the feistier one.



You could word it better still. SHE believed that all the specimens looked the same, until you asked about the elytra, and then I verified that I knew what that was, and then checked the 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 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 check, so long as it doesn't cost me a finger.

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!).

 

[ErinM31]

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.

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!

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!

 

[Hisserdude]

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.



Like diamonds!



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

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!

 

[BobBarley]

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

Oops! Lol

(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.

 

[Jacob Ma]

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.

 

[ErinM31]

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.

 

[Hisserdude]

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?

 

[ErinM31]

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?

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!

 

[Hisserdude]

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!

 

[Jacob Ma]

@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.

 

[ErinM31]

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.

 

[Jacob Ma]

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.

 

[Jacob Ma]

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.

 

[BobBarley]

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.

 

[Hisserdude]

@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!

 

[Hisserdude]

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.

 

[MWAInverts]

Agreed like the others, top two are males