Earlier this season, we shared an immensely popular post on our raised bed garden hoops. We only briefly mentioned “why” we use hoops on our gardens. Now we can show you.
In 2020, as prolific allium growers, we got hit by one of the worst pests an allium grower can face. The onion fly. (Sometimes also called the onion maggot.) This beast is the last thing any onion grower wants to deal with, it can literally spell “good night” to your entire allium crop in a single growing season!
When we got hit, we had no idea what we were dealing with. Like many of you might do, we turned to the internet to understand what was happening and what we could do about it. We learned two things. Our onions, garlic and leek were basically “destroyed” that season, it was all ready too late for us to do anything about it. The other thing we learned is that literally no one out there had *useful* information on how to recover from this infestation. The worst news? Once you have this bug, you always have it!
The general advice given to gardeners when they get the onion fly? Stop growing all allium for at least six years! Move your gardens at least one mile! It was like everyone out there had resolved themselves to “there’s nothing you can do!” Well, that’s not how we roll here at Frosty Garden. When the fight is brought to us, we’re keen to pick a fight!
We piloted a novel offensive and defensive strategy to try and navigate our way out. A major piece of this strategy is the hoops and bug netting you see here. This bug netting performs two major roles. It keeps onion flies out of our allium. It also traps the onion flies that emerge from our own soil from going anywhere they please.
The key thing we’re doing here is disrupting the mating cycle. Onion flies that are ready to lay their larvae simply cannot access our onions. Without access, the mating cycle cannot continue and those poor flies are left to find less wise northern allium growers to pick a fight with.
The logical among you might ask, “Well, what about those flies that emerged from your soil? They’re inside, with your onions, yeah?” Yes, and they can and will mate under the netting. But, they will be released into the wild, every few days, by briefly removing the bug netting. A wise reader did recommend we try vacuuming them up, which does sound appealing. Despite all appearances of the work we do here, we are “actually” lazy gardeners! (And that’s a lot of extra work of getting out equipment and chasing bugs!) Teaching is both easier and more effective!
We get a lot of these flies emerging from our soil starting in about mid June to early July, the peak of onion fly mating season in the subarctic. Up north here, we only get a single mating cycle. Whereas at lower latitudes, the onion fly can enjoy two mating cycles. (Typically May/June and August/September.) In case you’re curious about the “gross details,” the gist is that we have (literally) thousands of onion fly cocoons in our soil. These cocoons are expected to survive and produce onion flies for at least six years!
We learned this lesson the hard way. And we’re going to teach you all about it every single season. If you’re a prolific allium grower, this is a matter of “when” and not “if” it will happen to you. 50 below zero is not enough to protect you! Covering your allium crop is the only fully effective defense. If you want to be prepared, we suggest preparing like we do.
We’re navigating our fourth successive season after our onion fly infestation, which we’re proud to report has been very successful. We literally “wrote the book” on defending against and recovering from the onion fly. Many thousands of people have seen it and perhaps even followed our process. Give it a look, link is in the comments, if you want to know more!
