Japanese Beetle

The Japanese beetle is a scarab beetle in the family Scarabaeidae, subfamily Rutelinae, order Coleoptera. Native to Japan, it was accidentally introduced to New Jersey around 1916 and has since spread across much of eastern and midwestern North America.

It is notable for its extraordinarily broad host range, feeding on the foliage, flowers, and fruit of more than 300 species of plants, and for its habit of aggregating in dense feeding groups. This makes it one of the most recognizable and well-studied invasive scarab beetles in North America.

Ecologically, both the adult beetles and their soil-dwelling grub stage are important food sources for birds and small mammals, even as the species is widely regarded as a significant garden and turf pest.

• Oval, convex body with a shiny metallic green head and thorax
• Coppery-bronze wing covers (elytra) that do not fully cover the tip of the abdomen
• A row of five small tufts of white hair along each side of the abdomen — the most reliable field mark
• Short, clubbed antennae; body length about 8–11 mm
• Lookalikes include other green or bronze scarab beetles, but none combine the white abdominal tufts with this exact color pattern

Native to Japan, now established across much of the eastern and midwestern United States and parts of southern Canada. Adults are active in daylight during midsummer, roughly June through August. Larvae (white grubs) live in the top few inches of soil beneath turfgrass and lawns, where they overwinter deeper before pupating in spring.

Adults feed in groups during the day, chewing between leaf veins and leaving a distinctive lace-like skeletonized pattern. They locate host plants and each other partly through aggregation pheromones, leading to dense feeding clusters on a single plant. The subterranean grub stage feeds on the roots of grasses and other plants. Grubs are, in turn, an important food source for moles, skunks, and birds, giving the species a role in the broader food web despite its pest status.

Complete metamorphosis with one generation per year (univoltine) across most of its range. Eggs are laid in soil in mid-to-late summer; larvae (grubs) feed on roots through fall, move deeper to overwinter, then resume feeding and pupate in spring. Adults emerge in early summer to feed and mate, completing the annual cycle.