Birch Tree Carpenter Worms

If you  see this much Sawdust "frass" at the base of your tree "YOU MAY HAVE Carpenter worms"

This is a big problem when this much frass is found at the base of any tree.

Carpenter Worms

Problem: The larval stage of the carpenterworm is a large, wood-boring caterpillar that feeds within a tree’s inner bark on the sapwood. The earliest signs of an infestation are dark sap spots on the tree trunk. As the larvae feed within the sapwood, they expel frass (excrement) and sawdust out of the gallery entrance hole. This material is readily observable on infested tree trunks.

As the larvae grow, they expand the galleries. By the time the larvae are mature, the galleries are about 1/2 inch in diameter and 6 to 10 inches long; most of the gallery is vertical, except for the entrance area. Gallery entrances often are found in crotch areas of trees or in cracks and crevices in the bark. Adult females frequently lay eggs in areas of the tree that already are infested, and multiple galleries might arise in the same area, leading to extensive scarring on the corky bark tissue.

When mature, larvae can measure up to 1/2 inch in diameter and 2 to 3 inches long. They usually are greenish white with a dark brown head. They also have prominent hairs on their body, distinctive abdominal prolegs, and sharp, hooked legs on their thorax.

The adult carpenterworm is a large, robust moth with a wing expanse of about 3 inches. The forewings are mottled black and gray, making the moths difficult to see when they are resting on a tree trunk. The male moth is somewhat smaller than the female, and its hind wings are orange and brown while those of the female are off-w

Analysis: The extensive feeding of carpenter­worms in large branches can cause branches to weaken and break in high winds. The potential for dropping limbs is a major hazard in urban settings. Branch girdling by carpenter­worms, a process that disrupts a tree’s flow of nutrients and water, also can cause dieback of branches.

Solution:Provide trees with proper cultural care and protect them from injuries. Appropriate irrigation is especially important. Trees are better able to tolerate a few carpenterworms if they are kept vigorous.

If heavy carpenterworm infestations are suspected, have a qualified arborist inspect the trees. Because of the strong possibility of limb breakage as a result of carpenterworm feeding, heavily infested branches should be removed back to the point of attachment. In some cases, tree removal might be the best option.

It might be possible to kill the larvae by poking a long, sharp wire into the individual galleries, because a larva keeps its gallery open to the outside. This method is most practical when the infestation is small. However, it is difficult to know if the wire has penetrated far enough to kill the larva. To see if there is further larval activity after attempting to kill the larva, clear away any frass and sawdust material and mark the gallery site with a daub of paint. Recheck the site weekly to see if new frass material has been expelled. If so, the larva still is alive.

This tree went without water for 2 years at an abandoned house in Cedar City Utah. /the carpenter worm attacked this tree and now you can see the damage. We had to remove this tree.

Biological and Chemical Control

A very successful biocontrol option is the use of a single treatment of the beneficial nematodes Steinernema feltiaeor S. carpocapsae. While using nematodes might require additional monitoring and perhaps retreatment, they can be very effective in controlling carpenterworm infestations.

Except for nematodes, available insecticides are not effective against larvae beneath bark. Any other sprays must be aimed at adults, and successful control is difficult to achieve. Carefully monitor the tree bark at least once a week beginning in late winter, then promptly spray bark with an insecticide labeled for trunk and bark treatment when the first new pupal cases appear. There are very few pesticides that are labeled for carpenterworm. Homeowner products that contain a formulation of carbaryl or permethrin are available and might provide some control of the emerging and egg-laying adults if the material is applied when susceptible insects are present. However, because of the prolonged life cycle and varying development rates among individual carpenterworms, it will be necessary to repeatedly inspect bark and respray at intervals over a period of about 4 years or longer.

Do not spray trees unless comprehensive resources—including improved cultural care and an improved growing environment—can be provided long-term to reduce the likelihood of carpenterworm reinfestation.