Cryptorhynchus lapathi

The poplar-and-willow borer was initially found in the United States in 1882. A non-native insect originally from Europe, this species of weevil spread across the US, including in New England. The timing of the life cycle of this insect varies depending upon geographic location. In the northern most parts of its introduced range, such as British Columbia, it may take 2-3 years for the poplar-and-willow borer to complete its full life cycle. Typically, a single generation occurs per year in much of its introduced range. Pupation occurs in a pupal cell within the host tree, usually in the center of a stem, and most adult weevils emerge by the fall. Adults are the overwintering life stage in British Columbia, passing the colder months in the leaf litter or on the ground nearby susceptible host plants. In the Northeast, it is primarily the larval life stage that overwinters, in different instars (stages) in the sapwood of their host. By the spring and early summer, adult weevils become active on their hosts in British Columbia. In New England, the spring ushers in a period of rapid growth of the overwintered larva, causing it to resume feeding and expel multitudes of frass outside of a hole to the outside of the tree. Frass may be found clinging to the side of the trunk, or sap oozing from the holes created by the growing larvae. Trunks with frequent attacks may have many tunnels that form almost a honeycomb appearance. Pupation occurs in June. Egg laying occurs in July and August, with adult weevils most abundant in New York in August. Eggs are laid in holes or slits found on lenticels, branch bases, or near damaged bark. Eggs are white and tiny and laid for 4-6 weeks, often singly but in groups from 2-4 are possible. Occasionally, an adult weevil will survive through a second winter. Adults are most frequently active in the morning and the evening, and will "play dead" and drop to the ground if disturbed. Larvae are C-shaped in appearance, and 0.24 inches long.