The insect that causes the most harm to the evergreen tree is the bark beetle. A bark beetle is the most devastating of all insects. The bark beetle is commonly found throughout North American. There are eastern and western forms of the insect. The bark beetle will kill not only healthy trees but trees that have been weakened by a number of factors. The bark beetle builds egg laying galleries in the tree. What eventually leads to the death of the evergreen tree is the lack of sap flow. Once the bark beetle kills one tree the beetle will move on to the next evergreen tree.

A pale weevil is the top killer of newly planted pin seedlings which are most commonly found in the eastern part of the United States. The adult weevil is attracted to the pine lands that have been cutover. The weevil will breed in old root systems or stumps. The seedling is killed by the adult weevil that feeds on the stem bark. This is an insect that has been described as the ?most serious and economically ?destructive insect of seedling evergreen trees.

The spruce budworm is a native insect of the northern evergreen tree species found in the eastern United States. An outbreak of spruce budworms usually occurs every few years. The balsam fir, a species of evergreen tree, is the most damaged by the budworm. Outbreaks pf budworms have resulted in the loss of millions of evergreen trees. The newly hatched larva will feed on expanding buds and needles. This causes severe damage to the structure of the tree which eventually leads to the death of the evergreen tree.

The tussock moth is a dangerous insect that kills evergreen trees that are located in the western United States. The larva of the tussock moth will feed on the new year's foliage causing the foliage to shrivel, turn brown and to kill part or all of the tree. The tussock moth can kill up to one-third of the western species of evergreen trees and then go on to significantly deform the remaining trees.

The last deadly insect to the evergreen tree is the wooly adelgids. This insect affects evergreen trees in the eastern United States. The wooly adelgid has been known to kill entire stands of evergreen trees growing on critical sites. This is a sap sucking insect that will feed where the needle attaches to the twig. Researchers have concluded that the toxic saliva of the wooly adelgid is what causes the damage.

The evergreen tree is beautiful. There are preventive measures that an evergreen grower can take in order to prevent these insects from causing damage to the evergreen population. Also, there are preventive measures to take if you notice damage that has been done by one of these insects.