On the second-to-last day of March, snow fell overnight, and winter refused to leave. But spring was taking over, and by lunchtime, there was no trace of the fresh snow left. Seedlings were growing on the windowsills. This morning, I decided to add fresh soil to the pots and noticed tiny black flies flying out of some of the cups.
These seedlings are on the windowsill in the kitchen next to the green onions.
We grow onions on the windowsill all winter, usually growing green onions from our own onions. In the spring, when I plant onion sets, I plant the smallest bulblets near currant bushes or along the edges of the beds. We use some of these in the summer for greens, and we harvest the rest at the end of summer—they don't grow very large. I dry them and in the fall, when the Welsh onions in the garden freeze, I plant them in a small box, and we have fresh green onions all winter long.
Last summer, we ran out of onions; they rotted from the constant rain. We planted small store-bought ones, but one batch of them refused to sprout; most likely, they were frostbitten or diseased.
My husband kept adding water to the box, and soon the damp soil became infested with flies. We threw the onions out along with the soil, but since then, the flies have been appearing periodically in the onion box. They're not particularly troublesome; there are very few of them. And then these tiny flies appeared on the tomato seedlings. I decided to find out what kind of flies they were. They were sciarids, or flower gnats.
What do they look like?
These are small black or dark gray insects with a narrow body and a round head, long legs, and two transparent wings. Adults are 3-4 mm long, while young gnats are about 1.5 mm. The flies do not harm plants, but they lay eggs in moist soil, which hatch into larvae—white, transparent worms with a black head, 8-10 mm in size. They can damage young seedling roots.
It's very difficult to photograph fluttering mosquitoes; they don't like to pose, but I managed it. I killed some of them, but I also managed to capture a live fly.
This one flew out of the pot's soil and landed on a seedling leaf, and I took a photo using zoom. But this zoomed-in fly looks like a fruit fly, and it's not black at all.
I didn’t find any larvae in the box with onions, a breeding ground for sciarids, even with a magnifying glass.
And there are very few flies, they don’t fly around the rooms, they don’t poke our eyes out, they don’t end up in the soup, but we still have to fight them.
Where do they come from in the apartment?
They can be brought into an apartment through soil containing sciarid eggs; flies can fly in through an open window or through ventilation shafts from basements of apartment buildings. They can also be brought in with a new flower, which contains larvae in the soil.
In the winter, I often buy lettuce and other fresh greens in small pots and one day I saw several flies fly out of the cellophane packaging.
How to deal with them?
If there are few flies, you can use folk methods - lay out dry orange or tangerine peels, sprinkle the soil with cinnamon powder or ash, spread garlic slices in the soil, stick matches with sulfur heads into the soil.
If there are a lot of them, use chemicals - fly eater, thunder-2 - sprinkle on the ground.
Water the soil with a weak solution of potassium permanganate, ammonia, infusion of tobacco dust or ash, garlic.
I added thin slices of garlic to the box with onions, buried them in the ground, and sprinkled the soil with ash.
I didn’t add any chemicals—we eat the green onions.
I treated the tomato seedlings like this: I added fresh soil, sprinkled a little Grom-2 powder into the cups where the flies were flying out, watered them with a weak solution of potassium permanganate, and mulched them with dry soil. I stuck matches into some pots and sprinkled them with cinnamon powder, and placed tangerine peels in others.
I'll see if I can get rid of the flies on the seedlings.