NCCES - Christmas Tree Note #18 - Common Fraser Fir Insect Pests

North Carolina Cooperative Extension Service

CTN - 018

Christmas Tree Notes

Common Fraser Fir Insect Pests

Prepared by:

Jill R. Sidebottom, Extension Forestry
James R. McGraw, Extension Forestry

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Note: Many of these photographs are magnified, as the majority of the insects and their eggs are no larger than the head of a pin.

There are multiple images provided for your viewing: a smaller .gif version and a higher resolution, magnifed .jpeg version. You can access the .jpeg version by clicking on the smaller .gif view.

Balsam Twig Aphids (Mindarus abietinus)

The black balsam twig aphid egg is shaped like a teardrop and covered with white waxy rods. Eggs like this one can be found anywhere on the tree, although they are common in new growth. Eggs are present from June until they hatch in March or April. Once hatched, the green aphids feed on the underside of needles. At bud break, they move into the opening buds. They also feed on immature cones. The aphids, some of which have wings, are common from March to June. Needles damaged by balsam twig aphids will curl permanently if the damage is severe. If it is not, sufficient rainfall and nutrients will straighten many needles.

Cinara Aphids (Cinara sp.) Spruce Spider Mite (Oligonychus ununguis)

These large, dark brown aphids feed on shoots and terminals in the spring. Their feeding activities commonly cause a black fungus called sooty mold to grow on the tree. Heavy infestation can result in stunted, chlorotic (yellowed) growth. Adult spruce spider mites are dark red and have eight legs. They are seen in warm, dry, sunny weather feeding on new growth. To detect mites before damage occurs, use a hand lens and check current growth. As the spruce spider mite feeds on Fraser fir, it damages the needles with its piercing, sucking mouth. The needles become speckled, spotted, or dusty. They turn yellow, then brown, before they die and fall from the tree.

Balsam woolly Adelgid (Aphid) (Adelges piceae)

If the top of a Fraser fir appears flat or crooked, it may have balsam woolly adelgid damage. Look for easy-to-spot crooked tops after new growth hardens. Other symptoms include dead shoots, stunted growth, and stiff trunks. At harvest, look for red compression wood in the butt of the tree. Balsam woolly adelgid feeding causes the tree to form hard, brittle wood. Because the hard wood can no longer carry water and nutrients throught the tree, the tree eventually loses its needles and dies. If symptoms of the balsam woolly adelgid are observed, check the tree's trunk and trunk-branch union for white, woolly spots. These spots are the waxy coverings of adult adelgids. They can be seen on the tree year-round. This small, dark purple female lays eggs on the tree. Its feeding tube is permanently fixed in the tree's bark.

Rosette Bud Mites (Tricetacus sp.) Root Aphids (Prociphilus americanus) White Grubs (Phyllophaga anxia, P. fusca, and Polyphylla comes)

Because rosette buds are larger, hollow, and more rounded than normal buds, they are easily filled with hundreds of microscopic, eriophyid mites. As a result, rosette buds either do not break in the spring or break to form multiple, weakened shoots. Although root aphids feed on large roots, their feeding causes no damage. They are often associated with ants, which feed on the honeydew of the aphids. The ants create tunnels and galleries to reach the aphids, thus loosening the soil and sometimes damaging the trees. White grubs are the larva of scarab beetles. The grubs live in the soil and eat roots for two to three years before emerging as adult beetles. Adults lay eggs in short grass in May and June. White grubs are associated with pastures and will damage the roots of trees planted on these sites. Look for grubs in summer and fall by digging and sifting the soil.

	Balsam Twig Aphids (Mindarus abietinus)

The black balsam twig aphid egg is shaped like a teardrop and covered with white waxy rods. Eggs like this one can be found anywhere on the tree, although they are common in new growth. Eggs are present from June until they hatch in March or April.	Once hatched, the green aphids feed on the underside of needles. At bud break, they move into the opening buds. They also feed on immature cones. The aphids, some of which have wings, are common from March to June.	Needles damaged by balsam twig aphids will curl permanently if the damage is severe. If it is not, sufficient rainfall and nutrients will straighten many needles.
Cinara Aphids (Cinara sp.)	Spruce Spider Mite (Oligonychus ununguis)

These large, dark brown aphids feed on shoots and terminals in the spring. Their feeding activities commonly cause a black fungus called sooty mold to grow on the tree. Heavy infestation can result in stunted, chlorotic (yellowed) growth.	Adult spruce spider mites are dark red and have eight legs. They are seen in warm, dry, sunny weather feeding on new growth. To detect mites before damage occurs, use a hand lens and check current growth.	As the spruce spider mite feeds on Fraser fir, it damages the needles with its piercing, sucking mouth. The needles become speckled, spotted, or dusty. They turn yellow, then brown, before they die and fall from the tree.
Balsam woolly Adelgid (Aphid) (Adelges piceae)

If the top of a Fraser fir appears flat or crooked, it may have balsam woolly adelgid damage. Look for easy-to-spot crooked tops after new growth hardens. Other symptoms include dead shoots, stunted growth, and stiff trunks.	At harvest, look for red compression wood in the butt of the tree. Balsam woolly adelgid feeding causes the tree to form hard, brittle wood. Because the hard wood can no longer carry water and nutrients throught the tree, the tree eventually loses its needles and dies.	If symptoms of the balsam woolly adelgid are observed, check the tree's trunk and trunk-branch union for white, woolly spots. These spots are the waxy coverings of adult adelgids. They can be seen on the tree year-round.	This small, dark purple female lays eggs on the tree. Its feeding tube is permanently fixed in the tree's bark.
Rosette Bud Mites (Tricetacus sp.)	Root Aphids (Prociphilus americanus)	White Grubs (Phyllophaga anxia, P. fusca, and Polyphylla comes)

Because rosette buds are larger, hollow, and more rounded than normal buds, they are easily filled with hundreds of microscopic, eriophyid mites. As a result, rosette buds either do not break in the spring or break to form multiple, weakened shoots.	Although root aphids feed on large roots, their feeding causes no damage. They are often associated with ants, which feed on the honeydew of the aphids. The ants create tunnels and galleries to reach the aphids, thus loosening the soil and sometimes damaging the trees.	White grubs are the larva of scarab beetles. The grubs live in the soil and eat roots for two to three years before emerging as adult beetles. Adults lay eggs in short grass in May and June. White grubs are associated with pastures and will damage the roots of trees planted on these sites. Look for grubs in summer and fall by digging and sifting the soil.