Chip-wood Cocoon

In early July and up to September, the Peach Tree Borer Moth (Synanthedon exitiosa), emerges from its characteristic Chip wood Cocoon. Especially on days after a rain, when the soil is moist, the moth emerges in large numbers.

Adult females are larger than males, with a wingspan of an inch and a half and that of the male about an inch. The body color is dark steel blue. Bright orange white scales cover the fourth to sixth abdominal segments of the body. Female abdomens are stout and that of the male thin and narrow, with a tuft of scales at the tip.

Mating occurs rapidly and the female moth begins to lay eggs within half an hour after emerging. Eggs are laid on the trunks and the bases of trees. The eggs are reddish brown with hexagonally sculptured lines on the surface. A female moth lives for a week and may lay around 500 eggs. Egg deposition occurs during daytime.

Eggs hatch into larvae in 10 days, under warm conditions. Hatching may be slightly delayed during colder conditions.

The body of larva is light cream colored with a brown head. The larva has powerful mouthparts for boring through tree bark. The larva prefers the base of the tree trunk. After boring through the bark, the larva feeds on the cambium (cambium is a thin layer of generative tissue between the bark and the wood of the stem. It is a layer of actively dividing cells). The larva grows by molting. A fully-grown larva reaches a length of an inch and a half.

The larva now leaves the burrow under the bark. The burrow is full of fine wood particles as a result of boring. The larva collects this chip wood, secretes silk threads to bind the chip wood and constructs a tough cocoon. If the larva heavily infests the trees, the cocoons are found in the burrows. Otherwise, they are found lying on the top layer of soil, close to tree trunks.

Pupation lasts two to four weeks depending on weather conditions.

As the larvae feed on the growing tissue and inner bark of the trunk base, it results in the killing of young trees. Older trees lose vitality. The Peach Tree Borer moth is a pest causing severe damage to cherry, plum and nectarine shrubs of United States and Canada.

A similar moth, the Lesser Peach Tree Borer (Synanthedon pictipes) is also a major pest in fruit growing areas of US and Canada. The larvae of this moth look for wounds or injuries in the bark of the tree to bore through. They feed on the inner bark and cambium. The fully-grown larvae make chip wood cocoons with fine particles of wood cemented by silk threads. Pupation lasts 3 to 4 weeks. The moths cut the wall of the cocoon with mouthparts and emerge in late May through September in northern states. In southern states there may be two complete generations in a single year.