Stink bugs, belonging to the family Pentatomidae, are shield-shaped insects known for the foul odor they release when disturbed. Over 50 species are found in California alone. While some are beneficial predators, the majority are plant feeders, and the green stink bug is among the most common. Understanding their diet is crucial for managing their impact on gardens, crops, and landscapes.
Identifying Stink Bugs
Before delving into their dietary habits, it's important to accurately identify stink bugs. Adult stink bugs are characterized by their shield shape and a large triangle (scutellum) on their back. Their coloration varies by species, ranging from bright colors to uniform shades of brown, gray, or green. Eggs are barrel-shaped and laid in clusters, typically on leaves. Nymphs, the immature form, go through several instars, with coloration and markings changing as they develop.
Dietary Preferences of Green Stink Bugs
Green stink bugs are polyphagous, meaning they have a broad diet and feed on a wide variety of plants. Newly hatched stink bugs often begin by feeding on weeds and grasses. As they mature into adults, their diet expands to include fruits, vegetables, and field crops.
Preferred Food Sources
- Fruits: Stink bugs target various fruits, puncturing the skin and sucking out the juices. This feeding can cause blemishes, discoloration, and tissue damage.
- Vegetables: They also feed on vegetables, causing similar damage as they do to fruits.
- Field Crops: Stink bugs pose a significant threat to agricultural crops, leading to reduced yields and economic losses. Common crops they feed on include soybeans, corn, tomatoes, and peppers.
- Ornamental Plants: Stink bugs consume ornamental plants, including flowers, shrubs, and trees, by sucking their sap.
Feeding Habits and Damage
Stink bugs use their straw-like mouthparts to pierce plants and suck out nutrients. This feeding process can cause several types of damage:
- Blemishes and Discoloration: Their feeding causes blemishes, dark pinpricks, and other discolorations on fruits and vegetables.
- Tissue Damage: Damaged tissues become pithy and white, remaining firm instead of developing their normal texture and color.
- "Cat-Facing": On fruits like peaches and apples, stink bug feeding can cause cat-facing or dimpling. This occurs when the fruit is punctured early in its development, leading to deformities.
- Weakening of Plants: Stink bugs also feed on the stems and leaves of plants, weakening them and reducing yields. This damage can also create entry points for other pests and diseases.
Specific Examples of Stink Bug Damage
- Tomatoes: On green tomatoes, damage appears as dark pinpricks surrounded by a light discolored area that remains green or turns yellow when the fruit ripens.
- Apples and Pears: Tissue beneath feeding spots becomes pithy and brown or white, remaining firm as the fruit ripens.
- Peaches: Fruit turns brown and corky.
- Seedlings and Leafy Greens: Fed-upon seedlings and leafy greens may develop a tattered appearance.
- Okra and Bean Pods: Pimples or wart-like growths may appear, and blossoms and pods may drop prematurely. Leaves may roll, wilt, or be stunted.
Predatory Stink Bugs
While most stink bugs are plant feeders, a few species are beneficial predators. These predatory stink bugs feed on other insects, helping to control populations of crop-destroying pests. For example, the spined soldier bug (Podisus maculiventris) and twospotted stink bug (Perillus bioculatus) are known to feed on velvet bean caterpillars, root weevils, Colorado potato beetles, and even other stink bugs like the southern green stink bug.
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Stink Bugs in the Home
Stink bugs typically do not enter homes in search of food. Instead, they seek shelter from cold weather, especially during the fall and winter. While inside, they may feed on ornamental plants or any available produce, but they do not feed on people, pets, or household items.
Managing Stink Bug Infestations
Effective management of stink bug infestations requires a multi-faceted approach:
- Handpicking: For small plants, handpick the bugs and their eggs.
- Physical Barriers: Install row covers over plants to prevent stink bugs from accessing them.
- Natural Enemies: Encourage natural predators like birds and parasitic wasps.
- Organic Sprays: Use organic sprays like neem oil, insecticidal soap, or kaolin clay.
- Traps: Employ stink bug traps to reduce populations.
- Sanitation: Clean up plant debris after the season to eliminate overwintering sites.
- Vacuuming: Vacuum stink bugs indoors, especially in the early morning when they are slow-moving.
- Professional Pest Control: If infestations are severe, consider contacting pest control professionals.
Distinguishing Green Stink Bugs from Similar Species
The southern green stink bug (Nezara viridula) is similar to the green stink bug, but it has a small black dot in each lower corner of the scutellum and outer antennae segments that are mostly reddish. The consperse stink bug (Euschistus conspersus) resembles the brown marmorated stink bug and rough stink bug, but it has grayish legs with black speckles instead of white leg bands.
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