I have had very little success with my 2nd generation of mealworms for a couple months now since autumn. Almost all of the pupae have failed to pupate, most of which turn a hue of brownish orange and slowly die and turn dark brown or black and brittle. I have had only two successful beetles from probably hundreds of mealworms. I suspect this to be related to conditions, like room temp. Or humidity because it would correlate to the seasonal change. I know it can’t be the substrate or light because I have had a few separate batches in different grains and locations. Recently as spring has come, some of the pupae are Almost getting there, but they are trapped in their shell and if they do turn into beetles they become mutated and very limp, discolored, and their abdomen looks very empty. I have looked across the internet for info on this but could not find any conclusive or even usable information. I will note I have obtained these worms from my local pet store, but the first generation which was in August 2018 all became beetles with a few mutated individuals once and awhile but it is negligible and they were indeed from the store. This generation that is failing isn’t all just the 2nd generation after the successful beetle batch and their offspring, because I did get another batch and also another types of mealworm (potato beetle and buffalo beetle) the former having lackluster success but still having those problems and the latter doing just fine and flourishing in the same substrates with the same food (generally, I sometimes do feed them potatoes, the buffalo beetles getting carrot more frequently). I replace the worms’ food (potatoes, and carrots for small cultures) every other day. I don’t know if potatoes could be a culprit because i have been feeding them the same stuff since August. I at some point introduced styrofoam into their diets but I don’t think i did so before they had the issues. The buffalo beetles are not consumers of styrofoam but are doing fine, but I doubt that’d be the problem. I contain my mealworms in plastic sterilite bins in a cabinet and the smaller ones on top near a window, and I used oats at first but then now contain them in wheat bran and feed them potatoes every other day removing the old slices. I highly doubt the wheat bran would be the problem, but I could test a small culture in just oats to test. If anyone can help me understand what’s going on it would really be nice because mealworms are indeed a livestock for me as a hobby and potentially for money and/or human consumption and I like how they are much simpler easier to raise compared to the crickets which always died off with disease for me. I include images of the pupae and a temperature gauge below.
Meal worms will not pupate when in groups, they tend to keep in the larval stage and then die off as they age too long in larval stage.
Temp looks pretty good as does humidity, so I'm thinking they weren't separated so they would pupate.
It's a rather strange ecology for a larval organism but in laboratories, where they are used for class work, the larvae are kept together no more than 1 month then they are separated into small groups in large containers so they will pupate.
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