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Prevent common garden insects before they cause problems

Six images of diamondback moth during its different life stages on a green background. The first drawing is an adult diamondback moth with its wings outstretched. The second is a circular cutout showing eggs along a leaf being. The third is a small green larva. The fourth is a drawing of the pupal stage, which looks like a small green worm encased in a web with a leaf background. The final images are the adults again - one has its wings folded in, and the other has them outstretched.
Lifecycle of the diamondback moth. Illustrator: Martha Sudderth

There are many common insects that show up each year in our vegetable gardens. While we have plenty of strategies to prevent these insects from eating our veggies, they are much harder to manage once they’ve already shown up. As the weather warms up and you get ready to plant your gardens, now is a great time to plan ahead with some preventative management strategies.

We partnered with Carleton College art professor Eleanor Jensen and student Martha Sudderth to create two cropping calendars highlighting the most common insects of Brassicas (broccoli, cabbage, cauliflower, kale, mizuna, pak choi, etc.) and winter squash and pumpkins. The calendars show gardeners when to anticipate each insect and what the insects look like at different stages of their lifecycles. They also highlight management strategies. Check out the full, illustrated calendars

Tips to manage insects in your garden

  • Use row covers early in the season to exclude cabbage maggots and flea beetles from Brassicas.
  • Transplant large healthy plants that can withstand feeding damage better than slow-growing direct seeded crops.
  • Plant spicy trap crops like mustard and arugula around your other Brassicas to attract flea beetles.
  • Plant flowers and other native plants around your garden to attract beneficial insects.
  • Choose varieties of squash and pumpkin that are more tolerant to bacterial wilt, squash bug or squash vine borer.
  • Use straw mulch can help prevent various insects from laying their eggs in the soil, and support more diverse insect predator populations.

While none of these practices will eliminate insect pests from your garden 100 percent, they can help to reduce pressure, especially when used together.

Author: Natalie Hoidal, Extension educator, local foods and vegetable crops

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