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 overwhelmed gardeners. When 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. The Four-Spot Sap Beetle senses this aroma and will descend on the dying fruit/vegetable to feed on the residues. Where there is one Four-Spot Sap Beetle feeding, there are others on their way. 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 fruits and vegetables, preventative spraying of insecticide on plants as they grow does not prevent the beetle from coming. Only good garden maintenance stops the beetle from finding a produce patch. Removing diseased, spoiled and rotting produce at regular intervals effectively prevents the beetle from discovering 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.
Scientific Name: Glischrochilus quadrisignatus
Other Name(s): Picnic Beetle
Size (Adult; Length): 6mm to 11mm (0.23in to 0.43in)
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Antennae: Beetles have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and mandibles (jaws).
Thorax: Holds the three pairs of legs as well as vital internal organs.
Elytron: One of two wing cases on a Beetle that protects its wings (plural: elytra).
Wings: Appendages used for flying and kept under the elytra until needed.
Abdomen: Houses organs related to circulation, reproduction, and excretion.
Legs: Beetles have three pairs of legs located at the thorax, numbering six legs in all.