I plant my onions sets in April and everything's fine until the weather turns warm and dry. That's when the onion maggots appear. Pupae overwinter in the soil and hatch into flies (similar to house flies) by June. Females live for 30 days and lay 200 eggs. Now that's a lot of maggot potential even for my little garden!
Eggs are laid at the base of young seedlings. Larvae hatch and bore into the onion to feed (2-3 weeks) until it's time to pupate in the soil. If that's not bad enough, each growing season can produce three generations of onion maggot flies. It's a huge problem for commercial growers, but it's also a problem for us kitchen gardeners. If you eat onions fresh, you can cut out affected parts. But if you want to cure and store onions for later use, those affected by maggots don't keep well.
Methods to control onion maggots include:
- pull onions before the end of the third generation (August-October) so maggots cannot overwinter as pupae in the soil
- do not plant onions in the same place two years in a row
- do not plant all of your onions in one section of the garden
- water and dust seedlings with diatomaceous earth
- scatter ashes or sand around the base of seedlings
One thing we have plenty of around the cabin is wood ashes. I'm going to try the suggestion on my second planting that's just now sprouting. If it works, maybe this year I can nip the problem in the bud.
First I gave the onion bed a good watering. Then I spooned a light dusting of ashes all around the onion seedlings. It didn't say this in the book, but after several waterings or a heavy rain, it probably would be a good idea to reapply some ashes. Has anyone else tried this solution? Do you have any other suggestions for my onion maggot problem? I'll keep you posted on my results. -- Margy