Pacific Beetle Cockroaches


Diploptera punctata


Both the adults and nymphs are dark brown and have a beetle-like appearance. Male and female adults have well-developed wings that are dark-brown and covered with small pits. The wings cover the abdomen up to the last abdominal segment. Adult females are about 5/8 to 1-inch long, and the male is smaller than the female. This cockroach is also commonly called the cypress cockroach.


Pacific beetle cockroaches have an interesting behavioral habit of shooting a stream of irritating compounds to protect themselves from predators. They do not readily infest homes, but may be introduced inside along with infested plants. These cockroaches are serious pests of cypress, Norway pine and juniper trees in their area of distribution. In the process of feeding on the tree’s branches and bark, they girdle the tree and cause dead areas in the tree’s crown. To manage this problem, remove leaf litter from the crown and below the tree – locations that serve as nesting areas for Pacific beetle cockroaches.


The female Pacific beetle cockroach nurtures her offspring internally and gives birth to a brood of about 12 living young every 2-3 weeks. Females mate immediately after they become adults and are protected by the males.


The appearance of the nymphs, adults or their damage to tree crowns and other plants indicates an infestation.


Pacific beetle cockroaches are commonly found in landscapes of Hawaii. Also, this species may show up in plant materials that are shipped from regions of the world where the populations are firmly established.


Researchers often study the Pacific beetle cockroach in an effort to better understand the endocrinology of insect reproduction and development.