Stink bugs are a significant challenge for home gardeners, representing a persistent threat to a successful tomato harvest. These insects use specialized mouthparts to feed directly on the developing fruit, which drastically reduces the quality and marketability of the tomatoes. Protecting your crop requires an integrated strategy that combines proactive prevention, diligent manual removal, and cautious use of targeted treatments to minimize the population and limit damage.
Identifying Stink Bugs and Damage on Tomato Plants
Stink bugs are easily recognizable by their broad, shield-shaped bodies, typically measuring about a half-inch in length. While many native species are mottled brown or green, the invasive brown marmorated stink bug features a distinct striped pattern on its antennae and legs. These pests use piercing-sucking mouthparts to penetrate the tomato skin, injecting enzymes that liquefy the plant tissue. This feeding process causes the characteristic damage seen on the fruit.
Damage appears on green tomatoes as small, dark pinpricks surrounded by a light, discolored area that remains yellow or green as the fruit ripens. On a mature, red tomato, these feeding sites manifest as cloudy, yellowish-white spots just beneath the skin. Internally, the affected area becomes firm and spongy, often leading to a scarred, deformed appearance known as “cat-facing.” Early identification is important to prevent the loss of the developing crop.
Physical Barriers and Garden Management
Preventative strategies are the safest and most effective way to protect tomato plants from infestation. Fine mesh floating row covers provide a physical barrier that prevents adult bugs from landing on the plants to feed or lay eggs. These barriers must be installed immediately after planting and secured tightly to the ground. However, row covers must be lifted or removed once the tomato plants begin to flower, as the flowers require access to pollinating insects.
Maintaining a clean garden environment is also a powerful tool for population control. Stink bugs seek shelter in weeds, garden debris, and unkempt areas to overwinter. Removing nearby weeds and clearing fallen leaves or old crop residue in the fall eliminates these preferred hiding places. This sanitation effort reduces the number of adult bugs that emerge in the spring.
An effective, non-chemical method involves using a lure known as a trap crop to divert the pests away from your tomatoes. Plants like sunflowers or sorghum are highly attractive to stink bugs and should be planted approximately six to ten feet away from the main tomato patch. Staggering the planting ensures a continuously available, more desirable food source. The pests will congregate on the trap crop, which can then be monitored and treated separately.
Non-Chemical Methods for Active Removal
Once stink bugs are present, direct intervention using non-chemical methods can quickly reduce their numbers. The most common technique is hand-picking, which is most effective in the cool morning or evening when the bugs are less active. Simply knock the slow-moving insects into a bucket of soapy water, where they will drown. Alternatively, use a small, handheld vacuum cleaner for quick collection. Always dispose of the collected insects promptly to prevent the release of their defensive odor.
Encouraging natural enemies provides a long-term, sustainable form of biological control. Tiny parasitic wasps, such as Trissolcus basalis, lay their eggs inside the stink bug eggs, halting the pest’s life cycle. You can attract these beneficial insects by planting flowering herbs near your tomatoes, as the adult wasps feed on the nectar. Predatory insects like assassin bugs and praying mantises also feed on stink bug nymphs and adults.
A simple, non-toxic method for dislodging nymphs and adults is to spray them with a strong jet of water from a garden hose. While this will not kill the pests, it temporarily knocks them off the plant and disrupts their feeding activity. Repeated use of a strong water spray helps discourage the bugs from returning. This technique is best used on small infestations before the population establishes itself.
Applying Insecticides as a Last Resort
Chemical treatments should be considered only when preventative and manual controls fail to keep the population below damaging levels. If using an organic spray, focus on products containing insecticidal soap or neem oil, which work primarily through direct contact. These sprays are less effective against armored adult stink bugs and must be applied thoroughly to contact the more vulnerable nymphs.
For persistent, heavy infestations, a stronger treatment may be necessary, such as a product containing pyrethrins or permethrins. When using any chemical on edible crops, check the product label for the Pre-Harvest Interval (PHI). The PHI is the minimum number of days required between spraying and harvesting the fruit. To protect beneficial insects and pollinators, apply all insecticides late in the evening when they are inactive. Ensure the product is explicitly labeled for use on vegetable gardens and follow all safety instructions.