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

Latin Name: Carpophilus Lugubris

Appearance: The dusky sap beetle (DSB) is a dark gray beetle that is about 3/16″ long. The wing coverings are shorter than those of other beetles and do not extend all the way to the tip of the abdomen. Larvae are worm-like and creamy white, with a brown head capsule. The larvae of the dusky sap beetle grow in a variety of decaying plants. Vegetable fields’ discarded fruit and trash might be a favored nesting site. In wooded areas, dusky sap beetles feed on bacterial leaking from trees and decay pockets. The DSB spends the winter as a pupa in the soil or as an adult in protected locations. Adult DSB are active until late fall, then they become dormant until early spring, when they are present all year. Sweet corn adults may feed on tassels and pollen gathered in leaf axils.

Hosts Plants: Sap bugs are drawn to earlier developing sweet maize. Sweet corn that grows after the adjacent field corn has shed pollen has a reduced infestation. Dusky sap beetle is less likely to enter sweet corn cultivars with tight, lengthy husks.

Territory: They are found all across Europe and Siberia

Damage Insect Cause: The dusky sap beetle causes little harm to sweet corn kernels, and the damage is far less visible than that produced by maize earworm. Although dusky sap beetles frequently enter sweet corn ears through pre-existing wounds, they can also be found in sweet corn that has not been injured by corn earworm or other insects.

Life History and Habits: The life cycle consists of eggs, three larval instars, a pupa, and an adult. The development time from egg laying to adult emergence is around 7 weeks at 650F but may be finished in approximately 3 weeks at 850F. During high summer temperatures, sap beetle larvae can be seen with the naked eye as soon as three days after hatching. Eggs are elongate, creamy white, and scarcely visible without a magnifying glass. They are placed loosely beneath the husk or between the kernels. Adults can hollow out kernels towards the tip, and larvae can be discovered within these cavities when the eggs hatch. Larvae can also assault and feed within undamaged kernels.

Although dusky sap beetles can be found in sweet corn fields soon after silking begins, fields are not very appealing to insects until approximately 15 days later. When sugar production begins within the kernels and kernels begin to grow in size, sap bugs enter the ears. After this time, the vast majority of eggs are placed in the ears. Adult sap beetles are quite mobile in the field, and they frequently migrate from the ears after harvesting. When ripe corn is harvested and placed in a box, the majority of sap beetles leave the ears and travel around within the box.