Polyphaga saussurei die off

[scottbot84]

While checking my bids I thought to do a count of my Polyphaga saussurei, I started with maybe a dozen small nymphs and have had some slow die off (1 every two months or so), just infrequent enough it was easy to miss.

On this most recent check I lost my largest adult and smallest nymph, and have 4 large subadult nymphs remaining. Since this species is parthenogenic I just need one producing adult to keep my culture alive.

The odd thing is that I keep two other related species (P. aegyptiaca  and E. sinensis) in virtually identical conditions in adjoining bins that were started at the same time, and both are thriving with a good number of ootheca. 

Any thoughts on what could be the cause and what steps I can take to resolve it?

I have all 3 species in well ventilated 6qt bins with coco choir and hardwood leaves, feeding beetle jelly and koi food pellets. Jelly is always available and I keep one corner of the enclosure moist and leave the rest bone dry (misting the whole enclosure occasionally). I use a heat mat to provide a warm end of ~78F, the rest of the enclosure is room temp (~73-75F)

[Hisserdude]

I'd maybe consider making the moist area a bit bigger, maybe to cover a third of the substrate. That's the only issue I can personally think of. 

[scottbot84]

I'll try that, I was thinking I might have let their tub dry out a bit too much. The moist end is on a heating pad that seems to dry out the substrate even though it's on a thermostat and not on very much.

I'll turn down the temps a bit and add more water.

[Hisserdude]

Yeah heat pads/cables do dry the substrate out pretty quickly, I'd put the moist area on the opposite end of the heat source.