DW is a fan of green house plants. Summertime, they can be carried out to the greenhouse or under the shade of the porch roof. Divided, repotted – Autumn, back they come in the house. Back come the fungus gnats.
Bacillus thuringiensis soil surface treatment seemed to have been mostly ineffective on them. Yellow, sticky traps catch lots of the gnats but green house plants are intended to be attractive. Sticky traps aren't.
We think of the pests as "fungus gnats," only one kind, but they are not. This year and last, they are smaller than usual. Even to my untrained eye, I see the difference.
Aphids. We see the eggs on the underside of leaves, "ah, ha, aphids!" Is this the only place to find aphid eggs? Are there more than one aphid species? Of course there are.
One year, we had a population explosion of black aphids here at home. Never before but that year, they were everywhere! That has been about 6 or 8 years ago and never since. Are all the green aphids here the same species? I strongly doubt it. The University of Wisconsin says that worldwide, there are about 5,000 aphid species. Cabbage aphids can be a special problem in my garden. The University of Florida says the eggs overwinter in debris on the soil surface. You know, mulch ... humus, compost. Darn them!
Steve