I know it's an odd combo...
My son has two geckos- crested I think? Unfortunately I went to spray them this morning as he's away with work, and the female was lying dead on the floor of the viv :( The other is male but they're not old enough to breed- both about a year.
The reason I mention beetles is that the day he went away he found some in the viv that had appeared from nowhere. They were about a cm long, bright reddish brown lozenge shape, with black 'shoulders' and a little pointed head. I'm thinking maybe the female ate one and either they're poisonous or she choked as they were sort of rectangular and presumably hard. We did get rid of the 2 we found, but there may have been others hiding. Unfortunately as it was 1/2 hour before he had to leave for Birmingham, major clean ups weren't really an option.
All the branches in the tank are about a year old, so the only new things introduced recently are bark chippings (first lot of a new bag) and locusts (all eaten now). So maybe there were eggs or larvae in one of those?
I've cleaned out the spare viv and put the survivor in there, with no bark just in case and some thoroughly cleaned and checked plastic foliage.
Anyway, I suppose my question is whether anyone can identify the bugs or suggest any other ways I can ensure gecko 2 stays well. He is bright eyed and lively at the moment!