Spruce Needle Miner: Appearance, Territory, Damage and Life Cycle

Latin Name: Endothenia Albolineana

Appearance: The spruce needle miner’s symptoms include brown needles and webbing in little clusters that may be readily torn apart. Look for buff to reddish-brown discoloration, entry and exit holes, hollow and mined regions on needles. This little caterpillar eats inside the needles, traveling from one to the next and exiting via the small exit holes at the base of each needle. The needles that have fallen off amass in the caterpillars’ webbing. Damage is usually more obnoxious than fatal. Control methods include pruning contaminated stems and, if possible, destroying them.

Hosts Plants: Spruce

Territory: Native to North America

Damage Insect Cause: By hollowing out clusters of needles at the base and linking them together, a funnel-shaped mass of dead needles is generated. When many larvae eat at the same time, a vast pile of webbing and frass is produced. Larvae are 3/8-inch long pale greenish-brown caterpillars with a black head that can be seen near broken needles. Infestations in large trees are usually limited to lower branches, although minor tree tops can be damaged and defoliated as well. Landscape plants are significantly more susceptible to infestations than forest trees. In the early spring, if required, use an insecticide.

Life History and Habits: On the spruce needles, eggs are deposited like shingles. After hatching, the larva penetrates the needle’s base, hollowing it out. After thoroughly mined the needles, the larvae cut them off. The dead needles on the twig are held in place by dense matting of silk threads. Larvae eat on one needle after the other until they die. The larvae spend the winter within a needle at this time. They emerge in the spring and eat until pupation.