09/21/2026
Hey ya’ll! I wanted to address some of the recent discussion going around about the safety and nutritional value of peanut beetle larvae or PBL since I sell PBL cultures & use them as a staple feeder with my own jumping spiders.
Firstly, I can only speak for the claims I personally make about them, but I do want to share what the published literature actually says about Ulomoides dermestoides as well.
One thing I agree with is that I will never say any live feeder presents zero risk. Peanut beetle larvae have functional mouthparts and appropriately sizing prey is basic husbandry for any feeder insect. Where I disagree is with statements like “PBL can kill your spider,” “they will defend themselves by biting your spider,” or that they may opportunistically prey on an inactive spider.
I’ve been breeding these beetles for the past 10 months and regularly feed their larvae (and only their larvae!) to hundreds of jumping spider slings, juveniles, and adults. I have never personally experienced peanut beetle larvae demonstrating any of those behaviors. Being capable of chewing food or consuming vulnerable members of their own species under certain conditions doesn’t automatically mean they behave as predators toward jumping spiders. Making the claim that “because they have mandibles, they can kill your spider” is a hypothesis. It isn’t evidence that this is something that actually happens at any meaningful frequency.
My own experience is obviously anecdotal, but I think it’s worth contributing when personal experience is being used so heavily in the current conversation surrounding them. I maintain rack systems containing thousands of peanut beetle larvae and beetles. I routinely sift through them and have had my hands buried in cultures more times than I can count. I have never been bitten by a larva or had one latch onto my skin. That doesn’t mean I can prove it’s physically impossible, it just means one person having the opposite experience shouldn’t automatically be treated as proof that they present a significant feeder hazard either.
The nutritional numbers being shared about PBL also aren’t invented marketing figures. A direct analysis of P. dermestoides/U. dermestoides larvae reported approximately 54.95% crude protein, 18.24% crude fat, 2.8% ash and 24.08% total sugars, along with 47.4 g/100 g total amino acids and substantial mineral and trace element content.
https://hero.epa.gov/reference/366357/
They have a substantially higher protein-to-fat ratio than published analyses of standard mealworms, with their macronutrient profile being much closer to leaner feeders like crickets and fruit flies. That doesn’t make them a magical perfect feeder, but calling them a mealworm equivalent doesn’t really line up with the published numbers either.
And in regard to their climbing ability, larvae and beetles can absolutely climb textured material, substrate, peanuts, webbing, etc. What they generally cannot do is climb a clean, uninterrupted vertical smooth plastic surface. My own cultures are kept in smooth plastic trays without lids and I haven’t had an issue with them climbing out.
I can’t prove that a peanut beetle larva could never injure a spider under any possible circumstance, and I would never make that claim. But the reverse claim needs evidence too. I have not found published evidence, documented anecdotal reports, or anything in my own experience showing that appropriately sized U. dermestoides larvae routinely bite, attack, prey on, or kill jumping spiders.
For anyone using PBL, my advice is the same as it would be with any live feeder: use appropriately sized prey, use common sense around molting/injured/elderly spiders, and remove anything you’re personally uncomfortable leaving in an enclosure.
I’ll continue using PBL with my own spiders and selling cultures because both the published information available and my own experience support them as a nutritious, practical feeder when used appropriately. If credible evidence comes out showing otherwise, I have absolutely no issue changing my husbandry or the information I give customers. I care a lot more about being accurate than I do about defending something simply because I sell it! But I also don’t think speculation should be repeated as established fact just because it sounds biologically plausible. There’s a big difference between saying something could theoretically happen and saying something is a documented risk.
Photo is one of my Prim daughters enjoying her PBL 🥰
