Worms That Attack Pine Trees

The word worm is an obsolete term in biology, which refers to invertebrate (spineless) organisms that have no exoskeleton. As part of this group, the larvae (juvenile stage) of a number of insect species prefer pine as a tasty meal. Among these common pine tree predators are gypsy moths, weevils, pine tortoise scale, European pine sawfly, pine needle scale, and the common pine shoot beetle.

Gypsy moth larvae (Lymantria dispar) can defoliate large stands of trees. They prefer hardwood trees, but will eat pines if other food sources are not readily available. Gypsy moths lay their eggs in the summer, and the eggs hatch in late spring to early summer of the following year. Gypsy moth larvae typically feed for six to eight weeks before pupating and look hairy with a brown coloring.

Two types of weevil prey on pine trees, including the pine root collar weevil (Hylobius radicis) and the white pine weevil (Pissodes strobe). Both adult and larvae weevils drill through the bark of the tree until these insects hit the sap, which is their favorite food source. The white pine weevil mostly attacks Eastern white pine and Norway spruce, while the pine root collar weevil attacks a wider variety of pine trees. Pine weevils look like tiny white grubs.

Pine tortoise scale (Toumeyella) adults look like small tortoises, and they measure about a quarter of an inch long. Females can lay up to 500 eggs and their larvae hatch in late June. These insects affect pine trees by producing honeydew, which causes mold to develop on pine needles.

European pine sawfly larvae (Neodiprion sertifer) are found mostly on European pine plantations and have black heads with gray bodies. Infestations are usually minor, but pine sawfly larvae can still cause damage to pine needle leaves.

Pine need scale larvae (Chionaspis pinifoliae) lay eggs which hatch in early spring in warmer climates and in the middle of the summer in colder climates. These larvae measure 1/32 of an inch long and have a bright red appearance. Heavily infested trees must be removed as pine needle scale spreads rapidly, killing a number of conifer species.

Common pine shoot beetle larvae (Tomicus piniperda) was discovered in America in July 1992 and is the most common predator of pine trees throughout Europe, Asia, and North America. Reddish brown to black colored larvae kill pine growth by eating fresh shoots. Pine shoot beetle larvae burrow a hole into fresh pine stems and feed for almost two months. Their presence can be identified by looking for dying pine shoots with a hole in the center.