Named for the foul odor they release when squished, stink bugs typically don't damage lemon trees (Citrus limon, U.S. Department of Agriculture plant hardiness zones 9 through 11) unless they attack in really large numbers. Stink bug feeding activity can cause brown to black spots to form on rinds, and young lemon fruit often dry up and fall from the tree. Using physical, biological and chemical control methods can help you get rid of stink bugs before they reach populations large enough to severely damage your lemon crop.
Remove the Pests
Pluck stink bugs from small lemon trees and drop them into a bucket of soapy water. Although stink bugs don't bite, they do release a potentially irritating substance when disturbed. Wear work gloves, long sleeves and goggles to protect your skin and eyes. Don't crush the pests unless you want to smell their awful odor. If you're squeamish, suck the stink bugs into a vacuum cleaner with a disposable bag that you throw away immediately. Prevent future infestations by looking beneath the leaves for masses of 20 to 130, white, pale yellow or reddish-yellow eggs and squishing them with your fingers.
Spray Insecticidal Soap
Insecticidal soap is a less toxic way to kill stink bugs, but you must make direct contact with the pests for the chemicals to work. Start spraying in midspring and repeat treatments once a week throughout the growing season. Carefully read and follow label instructions. One insecticidal soap product recommends mixing 5 tablespoons of concentrate for every gallon of water. Use a small garden sprayer to thoroughly cover the entire plant with the solution.
Soaps can burn foliage, so avoid spraying trees in direct sunshine or in temperatures higher than 80 degrees Fahrenheit. Wear protective clothing and goggles to reduce your risk of chemical exposure. Spray on calm days when no rain is expected for 24 hours. Keep family members, including pets, out of the treated area until the solution dries. Insecticidal soaps kill off beneficial predatory insects and pollinators along with the pests. Apply soap solutions in the early morning or late evening when fewer good bugs are out and about.
Plant Trap Crops
Planting trap crops helps lure stink bugs away from your lemon tree. Consider using cowpeas (Vigna unguiculata) to trap bugs in the summer and mustard plants (Brassica juncea) to catch pests in early spring and late autumn. Once you spot a large number of stink bugs on your lure plants, plow the trap crop under or pull up entire plants, put them in a plastic garbage bag and allow it to sit in the sun for at least two days to kill the pests.
Understand Stink Bugs
The two stink bug species most likely to be citrus tree pests are the brown marmorated stink bug and the Southern green stink bug. Both species reach about 1/2 inch long and wide in maturity. The first type have mottled brown bodies, while Southern green stink bugs live up to their name with bright green bodies.
Keep in mind that pest stink bugs and predatory stink bugs look very similar. The spined soldier bug, a beneficial stink bug you want in your garden, looks very similar to the brown marmorated pests except for the spikes on their shoulders. Make sure the stink bugs on your lemon tree are actually pests before using any type of control measures.
- University of Florida IFAS Extension: Plant Bug Pests of Florida Citrus
- University of Florida IFAS Extension: Southern Green Stink Bug, Nezara Viridula
- Penn State Entomology: Brown Marmorated Stink Bug
- Cal Poly Urban Forest Ecosystems Institute: Lemon
- Toxic Free NC: About Harlequin Bugs and Stink Bugs
- ID Tools: Citrus Pests -- Brown Marmorated Stink Bug
- Organic Gardening: Stopping Stink Bugs
- Mississippi State University: Mississippi Forages -- Cowpea (Vigna Unguiculata)
- Photo Credit shulevich/iStock/Getty Images
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