Stink bugs are familiar insects in gardens and homes, recognized by their shield shape and the foul odor they release when disturbed. They belong to the order Hemiptera, commonly known as the true bugs. Aphids are also common garden insects, clustering on plant stems and leaves to suck out sap. Since these two pests often share the same habitat, many gardeners wonder if the stink bug might prey on the smaller aphid.
Stink Bugs and Aphids: A Direct Answer
The vast majority of stink bug species that cause problems for homeowners and agriculture, such as the Brown Marmorated Stink Bug (\(Halyomorpha halys\)), are strictly herbivorous. These common pests eat plants, not other insects, and their diet consists entirely of plant matter.
There are beneficial exceptions within the stink bug family known as predatory stink bugs, such as the Spined Soldier Bug (\(Podisus maculiventris\)). These predatory species consume other insects, including caterpillars, beetle larvae, and other soft-bodied pests. While aphids are potential prey, predatory stink bugs generally prefer larger, slower-moving insects like caterpillars, which offer a more substantial meal. Therefore, the common pest species seen in large numbers are not natural aphid control agents.
The Primary Diet of Common Stink Bugs
Common stink bugs are polyphagous, meaning they feed on a wide variety of plants, often exceeding 100 host species. They target economically important crops, including fruits like apples, peaches, cherries, and grapes. They also feed heavily on vegetables, such as tomatoes, peppers, sweet corn, and green beans.
The insects are particularly drawn to developing reproductive structures, including seeds and fruits. They damage soybeans by piercing the pods to extract nutrients from the developing beans. On corn, they feed directly on the kernels by inserting their mouthparts through the protective husk. This preference for high-value plant parts makes the common stink bug a serious agricultural nuisance.
In contrast, predatory stink bugs are specialized hunters that consume other arthropods. Their diet primarily consists of the eggs, larvae, and nymphs of plant-damaging insects, including moth larvae and immature stages of beetles. These species are considered beneficial because they help manage pest populations in the garden and in agricultural settings.
Feeding Mechanisms and Garden Impact
All true bugs, including stink bugs, possess specialized mouthparts known as a rostrum or beak, designed for piercing and sucking fluids. The rostrum contains four stylets bundled together to form a needle-like feeding tube. When feeding, the stink bug pushes this tube into the plant tissue to reach the sap or developing seed.
During this process, the insect injects saliva containing digestive enzymes into the plant. These enzymes break down the plant cells, allowing the stink bug to suck up the liquefied tissue and plant juices. This feeding process leaves distinct damage on the host plant.
On fruits like peaches and apples, localized tissue death and subsequent growth distortion results in depressions and scarring known as “cat-facing.” When they feed on developing seeds, such as those in soybeans, the feeding can cause the seeds to shrivel, become discolored, or fail to develop entirely. This physical damage results in necrotic spots, dimpling, and reductions in crop yield and market quality.