Yeah Lasius Niger seem to like fresh insects.
I just caught some sort of fly and put it in to mine and right away they grouped up and pulled it in to their test tube...still alive.
I also gave another colony mealworms.
A little tip though, mealworms aren't very good they have solid outer shells and are mostly liquid inside, mine didn't like that.
But they did like them in the pupae stage, for sure.
I cut off a pupae's head(they shake around if not) and put it in and they were at it all night, completely hollowed out the insides.
The pupae seem a lot more meaty than the worms anyway so if you get mealworms feed them and let them morph first.
Mealworms will eat pretty much any vegetable you give them, chuck a carrot in and watch it disappear over a few days. That way they turn in to pupae faster.