Strawberry Sap Beetle: Appearance, Territory, Damage and Life Cycle

Latin Name: Stelidota Geminate

Appearance: Strawberry farmers are occasionally confused by the existence of round, tiny, deep holes on the side of strawberry fruit. Small black insects are occasionally discovered inside the opening. This type of damage is characteristic with sap beetle injury. Strawberry sap beetle reports as a pest in strawberries have grown in the northeastern United States, paralleling a tendency toward producing a larger variety of fruit crops on individual farms. Strawberry sap beetles are a growing issue for strawberry farmers in the northeastern United States. The adults feed on ripe and overripe berries, causing holes, but more importantly, the larvae contaminate harvestable fruit, resulting in customer complaints and the necessity to halt the harvesting season early.

Strawberries can be harmed by many types of sap beetles. The most frequent of them are the picnic beetle (beer bug), the Strawberry Sap Beetle, and the Dusky Sap Beetle. The presence of knobbed antennae, which is typical across all sap beetles, is a significant trait in recognizing these insects. The mature Strawberry Sap Beetle is the smallest of the three, measuring around 3mm in length and is randomly patterned with brown colors.

Hosts Plants: Corn, Tomatoes, Raspberries, Strawberries and Muskmelons

Territory: Brazil

Damage Insect Cause: The cavities eaten by one or, more usually, a group of strawberry sap beetles are the principal damage produced by strawberry sap bugs. The beetles also disperse microbes that cause rots in the fruits and transport them to other fruits as they move. Any damage to the berries closes to harvest, such as other insects attacking the fruit or mechanical harm, might trigger an invasion of sap beetles. Larval damage is less visible since it occurs in rotting fruit, yet worm-infested fruit is of concern to growers and consumers.

Life History and Habits: Sap Beetles spend the winter in wooded areas, as well as among raspberry canes and blueberry plants. They do not appear to overwinter in strawberry fields, though. Beetles emerge from overwintering sites in the spring when strawberries ripen and are most active when temperatures above 16°C. Feeding is more prevalent on overripe and damaged berries, although Strawberry Sap Beetle damage is also common on ripe but otherwise marketable berries. Eggs are placed in the dirt around broken fruit, but even in half devoured fruit on occasion. This permits the larvae to eat for approximately one week before returning to the soil to pupate and grow into an adult sap beetle. The beetles reach maturity three weeks after the eggs are laid.