Red Turpentine Beetle

The eggs are cylindrical with rounded ends, white, opaque and shiny, and about 1 mm (0.04 in) long. The larva is a white, legless grub, with a brown head and brown tip to the abdomen. As it grows, lateral rows of pale brown tubercles become apparent. The fully grown larva is 10 to 12 mm (0.39 to 0.47 in) long. The pupa is white; it is exarate, the antennae and legs being free and not enclosed in a cocoon. The adult beetle is 6 to 10 mm (0.24 to 0.39 in) long and about twice as long as it is wide. When it first emerges from the pupa, it is tan, but it soon turns dark reddish-brown.

Dendroctonus valens occurs in North and Central America. Its range extends from Canada and the northern and western parts of the United States, southwards to Mexico, Guatemala and Honduras. In the mid-1990s it was accidentally introduced into China, probably in wood packaging material, where it became established; an outbreak occurred in Shanxi Province in 1999, and it has since spread to Hebei, Henan and Shaanxi Provinces. It has a wide potential host range that could allow it to spread to other parts of China and more widely across Eurasia.

In the southern parts of its geographic range, D. valens can be active all year with multiple generations being present in a population at once. Further north, these beetles are active from May to October and only have a single generation each year; in these regions, larvae can take more than a year to mature. On living trees, the beetles excavate a hole within a meter or two off the ground. Upon successfully reaching the cambium layer, a pair of beetles mate and the female excavates a vertical gallery, on one side of which she lays her eggs in small clusters. The beetles continue to enlarge their galleries while the eggs incubate. When the eggs hatch, the larvae tunnel out a large communal gallery in the phloem and cambium which becomes filled with frass. When they have completed their development, after two months or more, they pupate in individual cells in this chamber, or in short side galleries. The rate of development is dependent on the temperature. Galleries can span from the lower parts of the tree trunks into the upper parts of the root system and beetles inhabiting northern regions will go into the roots to hibernate in the winter months. …