I've been seeing a lot of black and brown tiny bugs on the stems and underside of the leaves of my green beans. Plants seem to be yellowing a bit. We have had a string of cold nights late into the season. Just this morning it was 39 now it's 65. I'm not sure if that has something to do with the little boogers on my plants or not. There are a few of the bugs on my Pintos. I'd like them to be gone !