Northern pitch twig moth
Jack, Lodgepole, Ponderosa and Scots pine
Appearance and Life Cycle
The moths are reddish-brown with greyish patches on the forewings. The wingspan is 15-25 mm. Adults are present throughout June and early July, depositing eggs at the base of needles on new shoots. The eggs are a lemon-yellow colour, flattened tear-shape and approximately 0.5 mm in diameter. Upon hatching, larvae bore into the succulent terminal shoots, where they form round, dirty lumps of pitch, frass and silk called nodules. Larvae feed individually within the nodules until late fall. After overwintering within the nodules, larvae resume feeding in May. In early June, larvae leave their original feeding sites and move to the nearest junction of branches where they resume feeding. At the point of attack, more nodules are formed, within which the larvae feed on the bark and cambium of the host. Larvae overwinter within the nodules and continue feeding in the spring until fully developed. Full grown larvae are reddish-brown with light brown heads and are approximately 15 mm long. Larvae pupate within the nodules and emerge as adults three weeks later, completing their two year life cycle.
Larvae feed on the bark and cambium layer of lateral and terminal twigs. The twigs are killed or so badly weakened that they are broken off by wind or snow. The insect generally attacks its host at a junction or whorl of branches. Damage to young trees may result in deformities or weakened, crooked trunks. Unsightly nodules of pitch, up to 40 mm in diameter are produced. These nodules formed at the fork of branches are an indication of a northern pitch twig moth infestation.
There is no insecticide registered for the control of the northern pitch twig moth. The only means of controlling the insect on ornamental plantings is to handpick and destroy the nodules before the moths emerge.
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