The brown marmorated stink bug (Halyomorpha halys) and other shield-shaped insects are common both outdoors and inside homes, often sharing space with various spider species. This frequent overlap leads many people to wonder about the ecological relationship between these two groups. The true nature of their interaction is far more one-sided than many assume.
Stink Bugs Are Strictly Herbivores
The vast majority of stink bugs, including the brown marmorated species, are herbivores, feeding exclusively on plant matter. This dietary focus makes preying on a spider biologically impossible. Their diet consists of a wide variety of fruits, vegetables, seeds, and the sap from trees and crops.
Stink bugs are highly polyphagous, which means they are not picky and can feed on over 100 different types of plants. They are significant agricultural pests because they damage crops like corn, soybeans, peaches, and apples by piercing the plant tissue and extracting internal fluids. This constant need for plant-based fluids is central to their survival.
A small number of species, such as the spined soldier bug (Podisus maculiventris), are predatory exceptions. These carnivorous bugs drain fluids from other insects, but they are not the typical shield-shaped bug found in homes or gardens. The common stink bug’s diet is strictly plant-based.
Specialized Feeding Mechanisms
The physical structure of a stink bug’s mouthparts confirms its role as a specialized fluid feeder. Stink bugs possess a piercing-sucking mouthpart known as a rostrum, or beak, adapted solely for penetrating plant tissue. This segmented structure houses four slender, needle-like stylets used to puncture surfaces like fruit skin or plant stems.
Once inserted, the stylets form two channels: one for injecting digestive enzymes and another for sucking up liquefied plant juice or sap. This apparatus is designed to handle liquid nutrients, making it physically incapable of capturing, chewing, or consuming the solid body of an arthropod like a spider.
Natural Enemies of Stink Bugs
While stink bugs do not eat spiders, the reverse ecological relationship is well-documented, with spiders acting as natural enemies. Several spider species, including orb-weavers, jumping spiders, and cellar spiders, prey on stink bugs. Spiders overcome the stink bug’s famous defense mechanism—the release of foul-smelling chemical compounds like trans-2-decenal and trans-2-octenal—by using specialized mouthparts or by quickly incapacitating the pest.
The unpleasant odor deters many predators, such as birds and reptiles, but some spiders consume the insect without being deterred. Larger spiders, like the fishing spider, and invasive species, such as the Joro spider, are effective predators of both adult and juvenile stink bugs. Other natural enemies include parasitic wasps, which lay eggs inside the stink bug’s eggs, and various species of birds.