Stink Bugs: How to Identify and Control them on Tomatoes
Stink bugs (sometimes called “shield bugs”) are pests that infest tomato plants and destroy fruit. There are more than 200 species in North America, all members of the pentatomidae insect family.
When threatened, these pests expel a repellent odor from their thoracic gland for which they are named. In short, they stink.
What does the stink bug look like?
Photo: University of California
Shape: shield-like Color: most are variations of brown or green Markings: different species can have yellow, red, or pink markings Size: about ½ inch long
What do they do to plants?
These pests insert their snouts underneath tomato skin. The enzyme they leave at the sting point turns that area of the tomato into liquid. The bug then drinks the liquid.
Sting points produce dark pinprick marks on the tomato.
Discolored areas appear on tomatoes where fluid is removed. They’re often white, yellowish or light green. Damage can appear knot-like.
When do they do their work?
Stink bugs are in their adult stage when they attack tomatoes.
How can you control stink bugs?
The best control measure is prevention (see below). Take other steps to keep these pests away from your tomatoes.
Control weeds. Excess foliage in the garden and adjacent areas provide perfect breeding habitats for the bugs. Keep your garden plot well-weeded beginning early in the season before the population matures. You'll to prevent them from taking up residence on your tomatoes. Continue to control weeds until harvest to keep bugs at bay.
Wash plants. When bugs first make an appearance in your tomato patch, spray tomato plants daily with water. The stream will force them off plants. You can also treat tomatoes with a 1-1 solution of water and vegetable oil, olive oil, or lavender oil applied with a garden sprayer to repel the insects.
Hand pick bugs. Remove them and drop them into a bucket of soapy water. You can place a tray beneath plant and shake it to collect bugs. Or use a hand vacuum to capture them.
Plant “trap crops” in an area around the tomato garden but set apart from the tomato plants. Trap crops are natural deterrents that draw stink bugs away from tomato plants and provide them with a thriving habitat. By planting abundant areas of small-flowered plants, you also encourage parasitic wasps, birds, and other predators that feed on the bugs. Stink bugs are known to be attracted to the color yellow. Mustard, millet, buckwheat, sorghum, sunflowers, marigolds, garlic, lavender, and chrysanthemums are good trap crops for these pests.
Use green treatment. Kaolin (sold as
) is a soft, white, silicate clay mineral combined with water and applied with
garden sprayers. After application, water evaporates leaving a protective powdery film. The coating acts as a physical barrier to insects, preventing pests from reaching tissue. Kaolin is natural and non-toxic. Treat tomato plants for two weeks before taking more drastic measures to control these insects.