What Is the Source of Root Maggots in My Garden

Question

I am having a problem with root maggots in my garden. They have all but destroyed my cabbage and brussels sprouts. They also have infested my onions.

I cut a small potato in half, and skewered each half on a stick. I then buried the potato halves in different parts of my garden. After 3 days, I pulled the potato halves up and examined them. I found one root maggot on one half and 3 root maggots on the other.

The potato halves were buried too deep for a fly to lay eggs. Unless the potatoes carried fly eggs, the maggots must have hatched from eggs in my soil.

Did I till-in fly eggs that overwintered near the surface? Did the fly eggs come with the composted horse manure that I tilled into my soil?

Answer 1

Yes, the eggs likely overewintered in the soil. Here is more information that should help with their control: https://www.gardeningknowhow.com/plant-problems/pests/insects/root-maggots.htm
https://www.gardeningknowhow.com/plant-problems/pests/root-eating-insects-identifying-vegetable-root-maggots-and-root-maggot-control.htm