bugs on evergreens
Spruce gall 'aphids'
Spruce gall 'aphids', often called wooly aphids, are actually adelgids. They cause galls (swellings) on the tips of spruce tree branches that resemble small green pineapples at first, then become hard and brown.
Spruce gall 'aphids' do very little damage - the tips eventually fall off or can be removed if considered unsightly. There is no chemical control.
Yellow-headed spruce sawfly larvae
Yellow-headed spruce sawfly larvae are small green caterpillars with orange heads that feed on young spruce needles in June. Branch tips with missing needles are unsightly and new needles will not replace those that are lost.
Yellow-headed spruce sawfly larvae can be controlled with a contact insecticide only when they are present. It may have to be repeated if more are seen later.
Web Spinning Sawfly
Web-spinning sawfly larva is a striped green caterpillar with a black or brown head that feeds on blue spruce needles during the summer. The masses of frass and debris they produce in the center of the tree are unsightly.
Web spinning sawfly webs and dead needles can be removed by a hard stream of a garden hose. By the time the damage is noticed the insects are usually gone. They cannot be controlled by a chemical unless it can be sprayed on the larvae.
Nesting Pine Sawfly
Nesting pine sawfly feed in groups on white pine needles and leave masses of frass, silk and dead needles at the ends of branches.
Nesting pine sawfly webs and dead needles can be removed by a hard stream of a garden hose. By the time the damage is noticed the insects are usually gone. They cannot be controlled by a chemical unless it can be sprayed on the larvae.
Larch Sawfly
Larch sawfly larvae are greyish green with black heads. The adult is a black sawfly with an orange band around the abdomen and orange marking on the legs. She inserts eggs into the elongating shoots of larch trees in early June, causing them to curl downwards. The developing larvae eat the needles.
Larch sawfly larvae cannot be controlled by a chemical because it cannot come in contact with them inside the branches.
Pine Pitch Moth
Pine pitch moth is found most often in association with western gall rust (see diseases). The larvae are greyish green with dark spots and reddish brown heads. Resin flow occurs from active galls as the larvae tunnel in below the bark, producing resin masses. The tunneling often causes breakage of branches.
Pine pitch moth galls should be pruned back to the next branch below the gall. The branch beyond the gall will die because water cannot get past the gall, and will usually break off in a strong wind.
White Spotted Sawyer
Whitespotted sawyer is a slender black beetle with very long antennae. It attacks dead and dying spruce, pine, douglas fir and larch. It feeds on bark and foliage, then lays eggs in cracks in the bark. The grayish-white larvae enter the sapwood of the tree and tunnel further into the tree for two years. Chips and frass are expelled through holes in the bark.
White spotted sawyer attacks only dead or dying trees and does no damage to living trees. No control is necessary.
White Pine Weevil
White pine weevil is a large white larva that lives within the leader of spruce trees and chews the soft tissue inside it. The leader curls over and the needles die by late summer. Small exit holes can be seen where adult weevils have emerged.
White pine weevil cannot be controlled by a chemical. If the leader is pruned back to just above a healthy branch, it can be bent up and tied to a stick to form a new leader.
Spider Mites
Spider mites are not insects but members of the spider family. They have eight legs, not six! They are small, either white or red, and form fine webs between the needles or between small branches. They can infest junipers and spruce.
Spider mites are not insects, but members of the spider family. Frequent hosing the tree with a hard spray of a garden hose can keep them under control. If chemical control is desired, use a mite killer, not an insecticide.
Aphids
Aphids can attack pyramidal junipers. They are rather large, black aphids, on the bark on the interior of the plant, so often unnoticed until needles become brown. They should be eliminated, as they can do considerable damage.
Aphids can be controlled with a contact insecticide sprayed well into the tree. Check the trees regularly for more aphids and spray as needed to eliminate them.
Pine Needle Scale
Pine needle scale is an insect that is covered with an elongated white covering. It attacks pine trees particularly. Eventually the tree becomes less healthy as needles discolor and drop.
Pine needle scale cannot be controlled by insecticides. The chemical cannot reach the insect underneath the scale. The tree can survive for may years with scale but there is a danger of it spreading to neighboring trees. A badly infected tree may have to be removed.