Webbing Coneworms: Appearance, Territory, Damage and Life Cycle

Latin Name: Dioryctria Disclusa

Appearances: Dioryctria Disclusa, often known as the webbing coneworm or rusty pine cone moth, is a Pyralidae moth species. Pinus species’ growing cones provide food for the larvae. They have a dark brown head and a thin black stripe across each abdomen segment.

The wingspan is approximately 24 millimetres. Inside the antemedial line, the forewings are yellowish orange, and beyond this line, they are deeper orange. The hindwings have a white fringe and are pale grey.

Host Plants: Pine forests and seed orchards are where they’re most commonly found. The larvae feed on the growing cones of various pine species.

Territory: From New Brunswick to Florida, west to Texas, and north to Manitoba, the webbing coneworm can be found.

Damage Caused: Mats of frass bound together by silk webbing on the outside of cones, as well as circular larval exit holes in cones, are signs of a coneworm infestation. Coneworm larvae feed on the cones and seeds of many coniferous tree species, including pine, fir, Douglas fir, and hemlock. In addition, cypress and hickory tree nuts are infested by coneworms. Coneworms burrow into cones and destroy parts of them, either partially or completely. Coneworm damage may be indicated by nonviable, discoloured cones. The coneworm tunnels and consumed portions are apparent when the cones are cut apart. Pitch flow, as well as insect webbing and frass, may be visible on the diseased cone’s external surface.

Life Cycle and Habits: In their life cycle, coneworms go through four stages: eggs, larvae (caterpillars), pupae (cocoons), and adults. Adult moths are tiny and go unnoticed most of the time. Adults are more active at night and are drawn to light. Larvae eat the cones or nuts of the host plant internally, although they may also eat needles and twigs. Larvae do not harm trees, but they do a great deal of damage to seeds and cones. Some species are highly mobile and will consume multiple cones. Cone and nut damage from feeding larvae ranges from tunnels to totally excavated chambers. The adults lay their eggs behind the scales of fresh cones or beneath the bark of the tree. During the summer, larvae feed and then drop to the ground in either the last larval (prepupae) or pupal stage to overwinter. Adults emerge as the weather warms in the spring, mate, and the female moth lays eggs. After about a month, the eggs hatch, and the larvae begin burrowing into and eating the cones and nuts. Coneworm species typically have only one reproduction every year.