Origin:
This is a native moth in North America.
Biology:
This native moth is found throughout southern Canada and the northern U.S., feeding on and sometimes causing serious damage to fir and spruce trees. The first instar larva hatches from its egg and immediately spins a silk cocoon in which it overwinters, emerging to feed in the spring. Early stage larvae bore into older needles and later instars feed on young buds, twigs, or developing cones. They create a silk tube that incorporates cut off needles and then pupate within this tube. The adults are active throughout the summer months and there is a single generation each year. Severe outbreaks of the moth occur sporadically, with long periods of many years often separating them.
Identification:
This is a relatively large species of moth for the family, with adult moths having a wingspan of around 1 inch. The forewings are mottled with a checkerboard pattern of light and dark gray patches. The larva is dark green to dark brown with 2 rows of white dots running along the top of the body.
Characteristicts Important to Control:
Natural controls such as parasitic flies and wasps will normally maintain populations of the moth below damaging levels, but favorable weather conditions may encourage the development of the larvae. Research continues on a number of biological control agents. Insecticide control may be necessary when severe outbreaks begin, using labeled products timed as well as possible with the emergence of the first instars that may be exposed. Later instars may be feeding within the buds and stems or within the protection of their silk tubes.
