Found some odd beetles in my millipede habitat, should I be concerned?

[TheOnlyScout]

So I just found these guys chowing down on some bug burger in my ivory millipede tank.
I'm not certain what they are at all, or how they even got in there.
They're about a centimeter long, they don't bite, they're very spastic, can't fly well or at all, and have a musk that smells like hospital disinfectant but fades to smelling like a circus beetle.
I am completely stumped. I know most of the species of insects, arachnids, and 'pods in my yard, and I've never seen these. The closest things I've found to them are mealworm beetles and darkling beetles but I'm not sure. Most beetles I saw either had a too defined thorax, or too squat antennae. I also dug around in the tank and didn't see any mealworms at all.
I'm slightly concerned because my ivories just had a massive clutch and I've probably got 100+ babies in there, making them very hard to move and very easy prey.
Does anyone know what they are and if I should be worried?


Additional info that may be helpful or I may be overthinking because it's 3am:
I'm in south Texas. I do use oak leaves from my yard, but I bake them first. I check my 'pede enclosure multiple times a day and have never seen them before. I also own a very old home that is prone to odd bugs getting inside. The millipede enclosure isn't totally impenetrable, but they're going to be moved to a tank where the airflow comes in through a mosquito net and the sides are well sealed. I've already had to fight isopods, fruit flies, and the roaches that live in leaves out of the tank. It's getting tiring, y'all. The only other bugs in the tank are springtails and some super tiny red mites that don't seem to bother the 'pedes. Which is good, because I cannot figure out how to remove them. If these guys are chill, I don't really mind them. They're pretty cute little guys.

 

[Albireo Wulfbooper]

Pretty sure that's some sort of Tenebrionid.

 

[Hisserdude]

They are combclawed beetles, a type of Tenebrionid, (darkling beetle), probably a Lobopoda species. Larvae feed on rotten wood, so I'm guessing some came in with some unsterilized substrate you used for the millipedes. Luckily it was those and not predatory click beetle larvae, this is why you should always sterilize your rotten wood, (unless you're keeping Brachycybe or some other kind of mycelium feeding millipede that require unsterilized, fungus covered rotten wood to survive...).

 

[TheOnlyScout]

They are combclawed beetles, a type of Tenebrionid, (darkling beetle), probably a Lobopoda species. Larvae feed on rotten wood, so I'm guessing some came in with some unsterilized substrate you used for the millipedes. Luckily it was those and not predatory click beetle larvae, this is why you should always sterilize your rotten wood, (unless you're keeping Brachycybe or some other kind of mycelium feeding millipede that require unsterilized, fungus covered rotten wood to survive...).

Thank you! I do sterilize my wood, which is what made this so confusing. I had this batch in the oven for much, much longer than was suggested... I'm not really sure what went wrong there.

 

[Albireo Wulfbooper]

Thank you! I do sterilize my wood, which is what made this so confusing. I had this batch in the oven for much, much longer than was suggested... I'm not really sure what went wrong there.

Interesting.

There are of course beetles which are adapted to fire-prone areas, and can survive more heat than one might expect, at least as eggs. I don't know if any Tenebrionids fall into this category.

 

[TheOnlyScout]

It's all been very odd. I want to say that I had them baking at 250 for around four or five hours. I may rebake that entire batch since it's the one giving me issues and I don't want them to continue into the tank I'm about to move them to.
I'm also reading that some poison dart keepers microwave theirs in water or between wet paper towels. I may try that and see if it doesn't kill everything even deader. Lol

 

[Albireo Wulfbooper]

Yeah, boiling should be very effective.

 

[TheOnlyScout]

That's what I'm thinking. I was in the, "250 for five hours will kill anything!" camp until this. Lol. Now it's time for the nuclear option. Especially since click beetles are plentiful in my yard.

 

[Hisserdude]

Thank you! I do sterilize my wood, which is what made this so confusing. I had this batch in the oven for much, much longer than was suggested... I'm not really sure what went wrong there.

Well another possibility is that a female beetle flew into your house, (they're attracted to lights), found it's way into the millipede tank and laid eggs in there.

 

[TheOnlyScout]

Well another possibility is that a female beetle flew into your house, (they're attracted to lights), found it's way into the millipede tank and laid eggs in there.

Also a strong possibility. As I said, I get a lot of bugs in this house. One of the reasons I'm moving them to a tank is so I can make a lid for it that will be easier to seal. I'm also going to move them away from the corner they're currently in.
They're on my console record player in my dining room currently, right next to the door to my kitchen. My kitchen is, typical of an old kitchen, a hot spot for lost insects. And that's the room with the backdoor that gets left open for the dogs regularly. New tank with air holes that are covered in mosquito mesh, relocated to the living room where I get less random insects, and re-sanitize the leaves and maybe my toils will be over. Lol

I will say, the Tenibreonid are cute, though. Maybe later on I'll do a beetle tank. The super literal Latin name gets me. Hahaha
I imagine them being the Batman of the beetles.