There are very small, yellow, clear-winged flies that hang out on my Ptelea trifoliata/wafer ash/hops tree. I grow it, because it's such a favorite host plant for giant swallowtails, and tiger swallowtails use it also. I saw this fly on top of one of the giant swallowtail eggs. I've been finding a lot of dud giant swallowtail eggs, so I'm wondering if this fly sucks out the inside of butterfly eggs? Could it be injecting something, like fly eggs, inside them, parasite fashion? I brought these eggs in to raise myself - they've turned dark, like they're about to hatch.

Here's the fly and eggs -

{{gwi:490688}}

Any help would be appreciated - giant swallowtails have been rare around the entire country this year, and I'd like to raise as many to adulthood as possible.

Thanks!

Sherry