What happened? Help identifying cause of death.

Hi,

Have any of you ever had something like this happen to their salamander:

The temperature and humidity are ok. The salamander looks well and is feeding well, until, one day she refuses to eat and the next day you notice she's more active than usual (or,at least, earlier than usual) and the day after that you realize all the food you put in her terrarium is dead. You take the salamander out of their ASAP, but, when you check on her the next morning, she is dead anyway.

In my case, the salamander was a yellow spotted salamander. I was in a bit of a hurry and I had no time to feed her earthworm, so I gave her meal worms (...bad, I know, but she usually accepts easily) and a cricket. It's possible the meal worms didn't die by themselves. They were in a clump, so she might have swallowed and vomited them, but the cricket looked unmolested and had barely moved from where I put it.

There were no wounds on the salamander.

I don't know what her age was because she was fully grown when I got her.

I've already checked with someone in my area who's very knowledgeable about salamander husbandry, but we weren't able to pin point the cause of death with any certainty, so I thought I'd check with a lot of people all at once, here.

Any ideas will be appreciated and kept in mind in the future.

I forgot to mention that no change was made to the enclosure recently and I had not handled any chemicals before touching anything in the enclosure.

Also, the substrate had been in there a while, but not overly long (and I scooped up the parts where she spent the most time twice a week). My leopard frog has spent a much longer time period on the same substrate without a problem. For both of them, the substrate is a commercial coconut fiber substrate. I was planning on changing it for a half/half mix of coconut fiber and natural top soil, but hadn't gotten around to it yet.

The leopard frog you mentioned, was it in the same enclosure?

How many mealworms were in the dead clump? Adult mealworms have powerful mouth parts. As individual snacks they are probably killed quite quickly by stomach acid. A large number of mealworms eaten at the same time might be able survive long enough to do some internal damage before they die.

Just a guess.

There were four meal-worms.

The frog is in a separate terrarium, but it has the same type of substrate.

I haven't fed any of these meal-worms to my other animals since then, and I will probably discard the batch, just in case there's something on them.