Strawberries are highly susceptible to damage from various insects throughout the growing season. Pests pose a constant threat from the moment flower buds appear until the final fruit is harvested, often drastically reducing the yield of a home garden. Understanding which insects are causing the trouble is the first step toward protecting your harvest and implementing targeted strategies.
Key Insect Pests Attacking Strawberry Plants
One of the earliest and most destructive pests is the Strawberry Bud Weevil, also known as the “Clipper.” This small, reddish-brown snout beetle emerges in early spring to attack unopened flower buds. The female uses her snout to puncture the bud and lay a single egg inside. She then partially severs the bud’s stem, or pedicel, to prevent it from opening.
The Tarnished Plant Bug (Lygus lineolaris) nymphs cause the most significant harm. These small, yellowish-green insects use piercing-sucking mouthparts to feed on the developing flowers and very young, immature fruit. This feeding injects toxic saliva into the plant tissue, which prevents the cells from expanding normally as the fruit grows.
The Sap Beetle (Stelidota geminata) arrives later in the season, drawn by the sugar content of ripening fruit. These small, dark-colored beetles are about one-eighth to one-quarter of an inch long. They are primarily attracted to ripe, overripe, or damaged berries, often dropping quickly to the ground when disturbed. The adult beetles bore into the soft fruit, often carrying fungal spores that hasten decay.
Recognizing Specific Feeding Damage
Diagnosing a pest problem begins with inspecting the injured plants and fruit for distinct patterns of damage. If you notice unopened flower buds wilting, turning brown, and falling to the ground, the Strawberry Bud Weevil is the likely culprit. The characteristic sign is the severed stem, or pedicel, just below the bud, where the weevil cut it after laying its egg.
Damage from the Tarnished Plant Bug is recognizable by the resulting deformed fruit, often called “cat-facing” or “button berries.” The mature fruit will be stunted and misshapen, with a concentration of exposed, hard, undeveloped seeds, usually at the tip. This happens because the feeding of the nymph stage on the flower or young fruit prevents uniform cell expansion.
If you find ripe or nearly ripe berries with large, irregular holes or deep cavities, Sap Beetles are the probable cause. This occurs just before or during harvest, especially where the fruit touches the soil. These beetles bore into the soft flesh of the berry to feed, creating tunnels deep within the fruit. This damage is frequently confused with slug injury, though the presence of the small, dark beetle confirms the diagnosis.
Managing Common Strawberry Pests
Controlling these insects relies on a combination of cultural and physical methods that disrupt the pests’ life cycles. Sanitation is a highly effective cultural control, particularly for Sap Beetles and Tarnished Plant Bugs. Regularly remove all old, damaged, or overripe fruit from the patch, as this material is highly attractive to Sap Beetles. Clearing away old plant debris and weeds also eliminates overwintering sites for adult insects.
Floating row covers offer a physical barrier against early-season pests like the Strawberry Bud Weevil and Tarnished Plant Bug. These lightweight fabric covers should be installed immediately as growth begins in the spring, before the flower buds emerge. It is important to remove the row covers once the plants start to bloom so that necessary pollinating insects can access the flowers.
For Sap Beetles, a method of hand-picking and trapping can help manage populations later in the season. Setting out simple traps containing fermenting fruit juice or overripe fruit a short distance from the patch can lure the beetles away. Promptly harvesting ripe fruit and avoiding the buildup of overripe berries on the ground is the most effective way to prevent a Sap Beetle infestation.