The bugs go as high as thermal lift goes. In the east that normally
goes to 8k or so - can go to 11k or 12K. Out west it can go above 18K
but middle teens is common.

When the bugs are there, the swifts will go there too. Usually don't
see them due to size unless you're flying in the same places, slow, and
with good visibility like a glider guider.

Heck, I've seen clumps of grass at 15K, 12kagl - dust devil debris I guess.

Ron Natalie wrote:

What has always impressed me is how high you find insects. I've
smacked into nice juicy bugs at like 6000'