Origin:
These are native moths in western North America.
Biology:
These two closely related species of moths occur in western North America, and feed within the trunks of many kinds of conifers. Their feeding generally causes no actual damage to the infested tree except when it is occurring at a junction of a limb, in which case it may weaken the limb and kill it or cause it to fall off. The main concern is the ugly white sap that runs out of the entry wound in the tree, often flowing in copious quantities down the trunk from that point and causing a loss of aesthetic value, or accumulating in a large blob on the trunk. Future female moths may be drawn to that point to deposit more eggs. Adult moths emerge from the overwintering pupa, which may extrude from the hole in the trunk, and have peak emergence in early summer. Males and females mate, the female deposits her eggs into crevices on the bark, and the adult moths live only a few days. They are active during the daytime. The larva then excavates a shallow cavity in the bark and eventually eats its way into the cambium layer, releasing the flow of sap. The life cycle normally takes 2 years to complete.
Identification:
The presence of the moths is normally done by the presence of the pitch masses or flow on the trunks of conifers. The adult Sequoia pitch moth closely resembles a wasp, with clear wings and a yellow and black thorax and abdomen. The adult Douglas fir pitch moth also resembles a wasp with clear wings, but its thorax, abdomen, and legs are black and red-orange.
Characteristicts Important to Control:
Chemical control is generally ineffective due to the larva being protected within the bark or under the sap layers. Keeping trees healthy will discourage females from laying eggs, as they are drawn to injured or previously infested trees. Physically removing the pitch blobs and killing the larvae is the recommended control. Pheromone traps are available to monitor for the presence of the adult moths, allowing for a timed application of a contact insecticide or a smothering oil insecticide to the trunk to kill the eggs or first instar larvae.
