Yes, stink bugs are a serious garden pest that actively feed on tomatoes. Various species, including the brown marmorated stink bug (Halyomorpha halys), target them throughout the growing season. These shield-shaped insects attack fruits at all stages of development, from small green tomatoes to ripe ones, causing damage that severely reduces their quality and marketability. Even low populations can ruin a substantial portion of a harvest.
How Stink Bugs Feed on Tomatoes
Stink bugs possess specialized mouthparts, known as a rostrum or stylets, which they use to pierce the tomato skin. Unlike chewing pests, they do not consume the external surface of the fruit. Instead, they use their needle-like mouthparts to penetrate the tissue beneath the skin.
After piercing the fruit, the insect injects salivary enzymes into the tomato flesh. These enzymes liquefy the plant cells and pre-digest the material immediately surrounding the feeding site. The bug then sucks out the resulting liquid contents and plant juices, including sap and nutrients.
This feeding mechanism causes the structural breakdown of the fruit tissue from the inside. The severity of the damage depends on the fruit’s size at the time of the attack. Feeding on tiny tomatoes can potentially cause them to drop prematurely.
Identifying Stink Bug Damage on Fruit
Identifying stink bug damage can be challenging because the initial puncture wound is often a small, dark pinprick that is hard to see. On green tomatoes, the feeding site may first appear as a light, discolored area surrounded by a darker ring. This discoloration is the external sign of the internal injury.
As the fruit ripens, the damage manifests as cloudy, yellowish, or white spots on the tomato’s skin. These spots, sometimes called “cloudy spot,” indicate where the bug inserted its mouthpart and extracted the contents. The visible spots can vary in size, sometimes merging to affect larger areas of the fruit.
If you slice open a damaged tomato, the internal consequences are visible beneath the external spot. The tissue in this area will be white, spongy, or pithy and will fail to ripen properly. This internal damage often turns into hard, corky tissue that makes the fruit inedible or reduces its flavor and texture. Furthermore, stink bugs can introduce yeast or other pathogens during feeding, which may lead to fruit decay.
Effective Strategies for Stink Bug Control
A successful control plan often starts with non-chemical methods to reduce the pest population and prevent access.
Non-Chemical Methods
Hand-picking is an effective initial strategy for small infestations, especially in the early morning when the bugs are sluggish. Collected bugs should be dropped into a container of soapy water, which prevents them from escaping.
Managing the garden environment is a highly effective preventative measure. Stink bugs often overwinter and breed in weedy areas, so removing common weeds like Russian thistle, mustards, and little mallow eliminates their shelter and breeding grounds. Physical barriers, such as fine-mesh row covers or netting, can also be used to physically exclude the insects from the plants during the fruiting period.
Targeted Treatments
For severe infestations, targeted treatments may be necessary. Insecticidal soaps and horticultural oils can be effective against the young nymphs but often have limited impact on the larger adult stink bugs. Low-impact products like kaolin clay can be sprayed onto the fruit to create a physical barrier that deters feeding and egg-laying. Chemical insecticides, if chosen, should be applied with caution, focusing on products that minimize harm to beneficial insects.