For beginners, I've ordered new screens for my apartment to keep them out, but I worry about what to do with the plants in their soil pots, where, no doubt, these bugs are laying their larvae. I'm thinking of getting a good broad-based pesticide and spraying the surface of the soil all over plants on this roof.

Any one out there have experience with this problem? Could you recommend a pesticide to kill the larvae or any other measure?

Biting midges/no-see-ums, etc. require moisture in order to breed. Most species aren't necessarily aquatic, but high levels of moisture is a must. Container growers need to be encouraged to be watchful about that.

These insects can all be controlled in the larval stage by the active ingredient found in common mosquito dunks : Bacillus thuringiensis var. Israelensis. Bt-I can be purchased as mosquito dunks, or in a granular form, or in a liquid form called Gnatrol. All of them need to be prepared and used when watering the plants normally. Bt-I, again, is a larvicide.

To avoid attracting the adults in the first place, it is always recommended that yellow lights be used instead of those that give off white light.