Dusky Sap Beetle

Appearance

A long lived species, the dusky sap beetle can live as an adult for up to 300 days. Measuring 3.3-4.5 mm, this large bodied beetle is primarily brown, but has orange colouration on its elytra. Depressions can be see on each side of the pygidium, which is a characteristic of males. Additionally, the genital capsule, which is quite distinct, can not be seen from an overhead view. Eggs produced by adults are milk coloured white and oval in shape. Similarly, the larvae can be white, or yellow in body colour with a brown head. This image, taken from Marini 2013, can provide a better look at the adult morphology and colouration.

Distribution

Native to North America, ''C. lugubris'' can be found throughout southern Canada, the United States, and as far as South America. Reports have even indicated its spread to southern European countries, such as, Italy. Only very cold climatic regions are free of the genus ''Carpophilus''.

Behavior

Like the typical beetle life cycle, ''C. lugubris'' has four life stages. The egg, larva, pupa, and adult. Eggs are often laid on the silk of corn and have a generation time of 2–4 days. 3-5 eggs will be laid at a time and the optimal temperature is 21 °C. The larval stage begins feeding on corn kernels and undergoes 3-4 instars before entering the pupa stage. This stage will often last for roughly 3 weeks. When ready to pupate, the larva fall to the ground and bury themselves. This may last 9–10 days before reemerging, but it can be longer if overwintering becomes necessary. Once exiting from the ground, the adult will use pheromones to locate a new food source and possible mating location.

Habitat

Like other sap beetles, fruit secretions are the primary food source, but they will also consume fungi, decomposing fruit and even pollen. ''C. lugubris'' is capable of feeding on undamaged fruits as well, corn being its primary food source. The species is long lived, so they will take up shelter in adverse environmental conditions. One such refuge is the bottom of bee creates, which are often closely located to crops. Going underground during the pupa and adult stages allows them to survive the winter. Larva and adults will often have overlapping niches, with the larva developing on the ears of the corn and eventually feeding on the kernels.