Pearl Sutton wrote:
Yeah I can't tell for sure. But they are kind of driving me crazy. I can't walk into my green house without them flying around my head. I did power wash them off once haha because I was annoyed but that didn't stop them haha. I'll try to get a better photo.
If your greenhouse is enclosed besides a vent they are probably getting trapped. It's going to be hard to keep them out unless you cover the vent with a screen. They look for ideal places to start their clay/dirt egg/larvae whatever they are called. They have to have them under shelter from rain and sun because if not they will wash away or dry out and their eggs will die.
If it is enclosed and you do have an unscreened vent. I would suggest try to screen it from the outside. If you screen it from the inside they will still build their nests in the vent area and it might make the vent not work properly or stop it from working all together until the nests are removed. I know some of the vent styles are protruding to the outside, so it might have to incorporate a frame for clearance.
If it isn't enclosed ... there is really no fix. They will always be there. I'm sorry. They won't hurt you.