The Brown Marmorated Stink Bug (BMSB) has become a familiar, unwelcome presence, known both as a household nuisance and a widespread agricultural pest across North America and Europe. This insect’s impact is directly tied to its unique feeding strategy. Stink bugs consume sustenance through a highly specialized mechanism that allows them to access the liquid nutrients and water stored within living plant tissues. Their life cycle and ability to feed on hundreds of plant species make them a significant concern for fruit and vegetable growers.
Specialized Mouthparts for Liquid Intake
Stink bugs belong to the insect order Hemiptera, commonly known as the “true bugs,” defined by their distinct piercing-sucking mouthparts. These specialized structures are adapted entirely for fluid consumption, not for chewing solid food. The external, segmented tube that protects these structures is called the rostrum, or beak, which is typically tucked beneath the insect’s body when not in use.
Housed inside the rostrum are four needle-like filaments, known as stylets, which are the tools for penetration. When a stink bug prepares to feed, it extends its rostrum and uses the sharp tips of the stylets to pierce the tough outer layers of a plant. This action creates a channel directly into the internal plant cells containing the desired fluids. The stylets form two separate channels: one for injecting saliva and another for drawing up the liquid food.
Primary Sources of Plant Fluids
The primary liquid intake for stink bugs is the internal sap and cellular juices of living plants, not standing water. They are highly polyphagous, meaning they feed on a vast number of host plants, targeting the tissues richest in moisture and nutrients, such as developing fruits, seeds, and pods. This feeding provides the bug with both hydration and the necessary sugars and proteins for growth and reproduction.
For agricultural pests like the Brown Marmorated Stink Bug, preferred sources include the internal juices of developing crops, making them a threat to orchards and field crops alike. They frequently target apples, peaches, sweet corn, tomatoes, and soybeans. The bugs seek out the reproductive structures of the plant, where the most concentrated nutrients are being stored. By focusing on these high-value parts, their feeding causes disproportionate damage to the overall crop yield.
How Feeding Habits Lead to Crop Damage
The physical act of piercing a plant is only the initial step in the damage process; the injection of saliva is the more destructive component. As the stink bug feeds, it secretes a mixture of saliva and digestive enzymes through one of the stylet channels into the plant tissue. These enzymes begin to break down the plant cells externally, turning the solid contents into a pre-digested liquid slurry that the bug can easily suck up.
This enzymatic injection causes localized death of the plant tissue, a condition known as necrosis. On fruits like apples and peaches, this results in sunken, misshapen areas often described as “catfacing” or internal cork-like spots. On vegetables such as soybeans, the enzymes can lead to shriveled, undersized seeds and a reduction in overall seed quality. Because the damage is caused by the chemical reaction and cellular breakdown, the resulting produce is often unmarketable due to severe cosmetic defects and poor internal quality.