Nicrophorus orbicollis is a nearctic burying beetle first described by Thomas Say in 1825. It is a member of the genus Nicrophorus or sexton beetles, comprising the most common beetles in the family Silphidae. This species is a decomposer feeding on carcasses of small dead animals. N. orbicollis can be used for scientific research both medically and forensically (if the beetle is present in the area).
Morphology/taxonomy
[[File:N. orbicollis metepimeron working.jpg|thumb|left|Lateral view of N.orbicollis''' setae and elytra.]]
AdultNicrophorus orbicollis is immediately recognized by its colorful orange markings on its elytra. The dorsal surface of the elytra is covered in long, fine setae, especially laterally, giving it a hairy appearance. The pronotum is spherical with wide lateral and basal margins. Its most distinctive feature from other Silphidae is its clubbed antennae with three orange apical segments and a black base. The posterior lobe of the metepimeron has a few brown hairs and the hind tibia is straight. The adult form is moderately sized at about long. N. orbicollis is known to be a saprophagous feeder. The adults feed on protein from smaller decomposing carcasses as well as supply these nutrients to their larvae.
Larva
Larval N.orbicollis differ from other Silphidae by widely separated labial palpi. They also contain ten abdominal segments with the sternum separated into sclerotized sternal units called sternites.
Origin
It is thought that silphids, including N. orbicollis, arose in the early Mesozoic and spread to southern parts of Pangea before the separation into Laurasia and Gondwanaland. It is believed that Nicrophorus species originated in the Old World and that most species related to N. orbicollis originated in Mexico and Central and South America.
Phenology and distributionNicrophorus orbicollis adults are active in the early spring with the first adult beetles emerging in late May. Reproduction occurs from June to August and teneral adults appear from late July to early August. This species spends the winter as an adult and is found mainly in open and forested habitats. Adults of the species are nocturnal. N. orbicollis is multivoltine with adults that care for their offspring during larval development. N. orbicollis is distributed from southeastern Canada to the southern tip of Florida and to East Texas; it has also been discovered as far west as Nebraska and as far north as North Dakota. N. orbicollis is the most frequently collected silphid species in the eastern United States. Adults can be collected from February to October but are most commonly found during the summer months from June to August as a result of their efficient activity in warm weather. Most N. orbicollis have been collected in mesic forest habitats on human and carnivore feces as well as on rotten fruit and carrion.
BehaviorNicrophorus orbicollis males will search for small bodies of animals such as chipmunks, rabbits, and toads in which to attract a mate. Once a body is located the male will proceed to climb onto the carcass and emit a pheromone to attract a mate. If another male enters the area, the two males will fight to the death and the winner will claim the carcass. Some males have been known to try to attract a mate without providing a carcass. These males will simply emit the pheromones even when they have not located a body. If females are attracted they will mate, but then continue to search for a mate that does have a carcass. Females are more likely to lay eggs fertilized by the most recent mate, so the males that have a carcass are more likely to actually pass on their genes. Once a male attracts a female, the pair will proceed to bury the animal carcass together, equally sharing the workload. If the carcass is too big for one pair, then it is acceptable for multiple pairs to work together to bury the carcass. Eggs are laid and buried very close to the carcass to provide a nearby source of nourishment. Unlike most beetle species, N. orbicollis parents will provide both food and protection for the larvae until pupation. It has also been observed that if one parent is killed the other parent will double up on the feeding and protection duties so the larvae do not suffer. Without parental care the larvae cannot usually survive until the point of pupation.