Tiny flying insects everywhere in my garden soil

Asked April 27, 2020, 12:50 PM EDT

Hello- Tiny, dark flying insects have infested my garden soil. I'm not quite at this point whether they are doing a whole lot of damage, but i am noticing more holes in my lettuce and difficulty in my beets and carrots growing (which is probably due to other factors). They really carpet the soil surface. What's going on here? Should I do something and if so, what? Thanks! Ethan Hasenstein Corvallis, OR

Benton County Oregon

1 Response

Hello and thank you for using Ask an Expert! The clouds of small black insects are probably fungus gnats. The adults are not harming your plants, they are more of a nuisance. Fungus gnat larvae eat algae and fungi that build up in the soil due to high moisture conditions and a lot of organic materials in the soil. Fungus gnat larva live in the soil and can harm plant roots. High amounts of moisture in your garden soils where there is an abundance of decaying materials encourage the growth of algae and fungi and attract the adults to lay eggs. You can trap the larvae using fresh cut raw potato pieces. Replace the pieces of potato every few days. The warmer the weather the quicker the life cycle of these critters. You can reduce their numbers by improving the drainage of your soils and cleaning up dead and decaying materials in the garden.. Avoid using incompletely composted organic matter. Minimize organic debris around crops. Avoid fertilizing with excessive amounts of manure, blood meal, or similar organic materials. Improve drainage of garden soils. Eliminate any irrigation leaks and standing water situations. There are commercially biological controls available, but these can be expensive and are better suited to greenhouse environments.