the house TD and I poked holes in all the bales and shot in boric acid poison mixes, then circled it all - but if they continue to hatch, we will have to eliminate the bales (a key element of our set, sadly) and subsititute either wooden boxes/crates or, per someone who does landscaping, bring in fake hay bales which have (hopefully) been treated.
In the meantime, after a week of notes and bug spraying attempts, we still haven't heard from our set designer abt feasible alternatives proposed by the house (and me)....
PSMKay, house is purchasing the product for after the bales leave, when they will be chasing the little buggers down. Thanks for the lead