My brother planted some hops two years ago. I use them to shade the house. I had a crappy harvest of hops but it was enough to inspire me to brew some beer. I did an extract brew kit so I didn't use the hops I harvested but I wanted to know something. In CA we have hot dry weather in the summer and I am in the original hop growing region of CA. This happens to be the best place to grow Two Spotted Spider Mite. They got all over my vines but resided mostly on the leaves. I'm sure some low level of mites worked their way onto the cones but not to the level that they started tenting with their webs. If I were to brew some beer with these would it in any way ruin the flavor or cause contamination in the beer? Should I toss them or keep them.
I wouldn't be so sure that your commercially packaged hops from a kit didn't have some insect traces in them. A lot of crops have a limit as to how many insects they can have per any given weight. Think about peanut butter and corn chips for example. Yum.
I can't say I've had much problems with mites specifically but as far as the infection goes, that is what boiling is for.