OK this is sooo sad. We bought DS an Ant Farm for his 4th birthday and predictably he has no interest in it and I end up thinking "ooh mustn't forget to feed the ants..." which is not something I ever thought I'd hear myself think.
Anyway you have to feed them small pieces of fruit in external feeding stations. They have so far enjoyed banana, apple, peeled grape and strawberry. Normal situation is that they eat some for a day then the fruit goes mouldy and the ants just stay in the soil (where you can't see them).
But when I put some strawberry in there - it didn't go mouldy and about 6 ants just sat around it looking lazy and eventually 4 of them died. Do you reckon it fermented and the ants got pissed? Made me laugh - what else ferments?