Wednesday, July 25, 2012

Guide to Identifying and Controlling Squash Bugs Organically

Image: Squeezyboy/Flickr
Squash bugs, commonly called “stink bugs,” are known for the odor they emit after being squished, but gardeners know that there’s more to these garden pests than their smell; they invade vegetable gardens and make themselves at home as they chew on plant stems and suck on their juices. Fortunately for the organic gardener, there are 7 ways to control the squash bug population without using a drop of pesticides.

How to Identify Squash Bugs

Eggs: Squash bugs lay their eggs on the undersides of leaves in small clusters. Newly laid eggs are shiny yellow in color while mature eggs are brick red.

Nymphs: Nymphs start life pale green in color and turn gray as they age.

Adults: When these garden pests turn into adults, they grow to ½ inch in size. Their bodies are oval shaped and either dark brown or black in color.

When Squash Bugs Attack

The life cycle of a squash bug happens over the course of a year, which is good news because this limits them to producing 1 generation a year. Spring is the time these garden pests lay their eggs. 1 to 2 weeks later, they hatch into nymphs which take about 4 to 6 weeks to grow. When winter rolls around, adult squash bugs burrow under garden debris or anything lying on the ground that will give them shelter.

Common Plants Squash Bugs Attack

Nymphs and adult squash bugs will suck the juices from the following plants, attacking stems and vines.

  • Squash
  • Cucumbers
  • Pumpkins
  • Gourds
  • Melons

How to Identify Squash Bug Damage

There are telltale signs that squash bugs are present in the garden, organic or not. Vines and stems have obvious “bite marks” which look like ragged dents. Leaves of plants begin to wilt, turn black and eventually die. This can happen to young shoots as well.

7 Ways to Control Squash Bugs Organically

1. Plant Resistant Varieties of Plants: Check with the local plant nursery, consult seed catalogs and gardening websites for plant varieties that are resistant to squash bugs.

2. Handpick Bugs: Check the undersides of plants regularly and handpick any and all eggs, nymphs and adult squash bugs. Carry a bucket or bottle of soapy water and drop the garden pests inside where they’ll drown. This is a great way to control pests organically.

3. Use Trellises: Grow plants along trellises to keep vines off the ground.

4. Utilize Boards/Cardboard: Place boards or pieces of cardboard around plant stems. In the early morning, lift the boards and handpick or squish any bugs that spent the night under the boards.

5. Tachnid Flies: Attract tachnid flies by planting sweet fennel, parsley, clover, dill, goldenrod, buckwheat, wild carrot and amaranth around the garden. The flies are a great way to control squash bugs organically because they lay their eggs on the backs of squash bugs where they hatch, borrowing inside the garden pest.

Tachnid fly larvae produce more flies which will eventually wipe out about 80% of the adult squash bug population. Leave infected adults be so the eggs can hatch and continue the tachnid fly life cycle.

6. Remove Garden Debris: Come fall, clear the garden of all debris including dead plants, boards and anything else adult bugs can over winter under.

7. Floating Row Covers: Use these to protect young plants. Once plants flower, the covers will have to be lifted for a few hours each day to allow for pollination. Once plants begin steadily growing, remove the floating row covers all together.

Controlling squash bugs organically is a 3 season process. Begin in the fall by cleaning up the garden and check for and remove squash bugs in all stages of life throughout the growing season.

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Reference: Rodale Organic Gardening (2001). Basics:Pests Volume 7. Rodale Inc.

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