When do whiteflies typically emerge?

Question

When do whiteflies typically emerge in southwestern Idaho? (How far into the season, I mean.) I don't know if they're gone or if they just haven't hatched, yet. There's no sign of them, yet. They infested our grapes last year, but I didn't know they were pests (or even that they were there) until late summer when a friend told me.

I released a bunch of ladybugs, and we have lacewings about. The grapes are looking good (and we actually have a fair amount of fruit growing; we got one or two clusters last year--much less than before). I also gave them some worm castings, this year, because I heard a rumor from an Amazon review that they help protect against whiteflies. I also added basalt rockdust and potassium sulfate for added insect resistance. (Potassium, calcium and silica help plants become more insect resistant, I've read.)

EDIT: I just saw a few whiteflies, today, and perhaps a few larvae. So, I guess they begin emerging in southwestern Idaho by June 18th. I'm not sure how long they've been around, though, so I'll leave this in case someone knows the earliest time they emerge.

One remarkable thing I noticed is that the leaf pests on the grapevine are mostly only affecting the leaves in the shade. The ones in the sun are, relatively speaking, pest-free.

Answer 1

An issue with whiteflies is that they don't have a yearly time of emergence, and so are not nearly as easy to prepare for as some others. They hatch when it's warm enough, which varies from year to year. This is usually when temperatures stay mostly above 60 degrees F.

And then they cycle quickly through life and multiply rapidly throughout the season they can tolerate. It varies every year, and in some areas they can be a year round problem.