Four-Spot Sap Beetle (Glischrochilus quadrisignatus)
Detailing the physical features, habits, territorial reach and other identifying qualities of the Four-Spot Sap Beetle.
Updated: 5/21/2015; Authored By Staff Writer; Content ©www.InsectIdentification.org
The varied diet of the Four-Spot Sap Beetle makes them both friend and foe of the backyard gardener.
Four-Spot Sap Beetles feed on the larvae of tree-boring beetles. This makes them somewhat of an aborist's ally in maintaining tree health. They can become a nuisance, however, if they catch the scent of spoiling vegetation in the garden. This species of beetle will take advantage of lazy or overwhelmed gardeners. If fruits and vegetables are left on the vine to rot, or fall victim to a disease and begin to spoil, they release volatile chemicals into the air and the Four-Spot Sap Beetle will descend on the dying fruit/vegetable to feed on the residues. When one Four-Spot Sap Beetle begins to feed on an overripe garden, many others quickly join. This can lead to an infestation. Though they do not attack healthy produce, their large numbers can quickly get out of control and make them a difficult pest to eliminate. Since they do not feed on healthy, growing fruits and vegetables, spraying plants as they grow does not prevent the beetle from coming. Only good garden maintenance does that. Removing diseased, spoiled and rotting produce at regular intervals effectively prevents the beetle from finding a garden.
Adult females will lay eggs on decaying plant matter after they emerge from overwintering. The eggs hatch sometime in June or July and the larvae feed on whatever plant material is near them until they pupate. Once they become adults, they seek out food sources. Vegetation damaged earlier in the season by other types of insects, like beetle or moth larvae, allow the Four-Spot Sap Beetle to immediately begin feeding at the areas of the existing wounds. They are secondary invaders of many types of important agricultural crops like corn and strawberries. Large numbers of them have been known to spread a fungal infection to the crops which further reduces a healthy harvest.