How to Grow: Controlling Summer Beetles

Learn about the best organic controls for the asparagus beetle and flea beetle.

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beetlesIn Vermont, we wait months for warm weather to go outside. And as soon as it’s warm, the bugs are out. For our plants, it’s no different. Here are two beetles that are out in force right now.

Asparagus beetles emerge with the spears in early spring. This oval, red or black beetle with black or white spots feeds on spears. It also lays elongated, brown eggs. As the spears grow into ferns, the eggs hatch into black larvae that defoliate the plant. The ferns are important because they rejuvenate the asparagus plant for next year. The feeding of the adults causes browning of the spear tips and a shepherd’s crook of the spears. Control these beetles by hand picking adults in spring and rubbing the eggs off the spears. Parasitic flies, ladybugs and birds will all feed on asparagus beetle larvae and adults, so avoid spraying pesticides unless absolutely necessary. You can also destroy their overwintering sites by cutting old ferns to the ground and cleaning up mulch and plant debris.

Another beetle you’ll see now is the flea beetle. This black beetle hops when disturbed, hence the common name. It’s feeding causes shotgun-like holes in the leaves of seedlings such as broccoli, cabbage, eggplant, and melon. If severe, it can kill the seedling. They’re really only a problem in spring, so if you can protect your seedlings until larger, they should survive. Control flea beetles by cleaning up plant debris and covering plants with a floating row cover. Plant a radish trap crop to attract them away from your main crop and spray the trap crop with spinosad in the evening.

From the Vermont Garden Journal.

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