I have noticed on my asparagus plants quite a few dead flies. I know what asparaus beetle looks like, I have been picking them off and killing them on sight this year and my asparagus looks much better for it. But these are just "ordinary" flies, and it looks like they have flown onto the ferns and died there. And I have a houseplant asparagus, and just noticed a fly has died on that too! What is going on?