Butterflies - predacious hornets

[David Albaugh]

I have been rearing butterflies and moths for years and this is the
first time I have had a problem with wasps/yellow jackets.
I rear larvae 2 ways: first in sleeves on the host foodplant and second
on branches of the host put in a 2 liter soda bottle with some water and
Miracle Grow (these are kept in a screened-in gazeebo tent and are also
sleeved). This year I found yellow jackets eating larvae through the
fine mesh of the sleeves. Today I found wasps landing on the side of the
tent where the most caterpillars are. I can understand the sleeves
outside of the tent - the larvae might be climbing on the inside of the
sleeve or on a leaf against the sleeve and the wasp has an instant meal.
With the gazeebo how the heck do the know they are in there - can they
actually hear them chewing?