Trees in Red Deer are under attack.
The yellowheaded spruce sawfly population is feeding on the foliage of young Engelmann, white, black and blue spruce trees.
Some of the badly hit areas are along the north end of Taylor Drive,, Edgar Industrial Park, Kentwood and Johnstone Park perimeter trees.
Elaine Johnson, City of Red Deer urban forester, said residents near those areas should be checking their smaller spruce trees for yellowheaded green caterpillars. The pest can be between 16 and 20 mm long with yellowish-brown heads and shiny olive green bodies with paired greyish-green lines on the length of the body.
Johnson said the rainy weather in recent weeks or the lack of control management in some areas of the city may have played a part in the increased populations. The little pest can kill a tree and increase trees’ susceptibility to disease and other pests. Johnson said the female saws a little hole in the tips of the tree and lays eggs. The eggs hatch and they begin to feed on the foliage of the tree.
“It’s just a matter of getting them off,” said Johnson, noting the caterpillar is a native species to Alberta. “The trees should be fine if you can get rid of the caterpillars. Lots of times the trees will flush out new buds because they have dormant buds under their bark. They will be just fine just as long as they don’t leave them for three or five years. The tree will be completely defoliated. The tree can only take so much. And then it will just give up.”
A telltale sign the pest has visited your spruce tree are brown needles starting at the tip of the branches, something not typically seen, especially this time of year. The caterpillar generally attacks young landscape trees that were planted in the last eight to 10 years.
The caterpillars are active in early to mid-summer and can also be controlled at this time.
Johnson said management of the pest will help control the spread. Some measures include spraying the infected tree with high pressure water, hand-picking larvae off trees and pruning branch tips where the larvae live and disposing of them in sealed garbage bags. If residents are considering chemical control, they should ensure the caterpillars are present.
“I really encourage people not to start spraying without seeing something there,” said Johnson. “If they are not sure, take a sample to a local garden centre and ask if they can help identify the bug.”
Johnson is handing out information letters in areas where she spots the caterpillar.
For more information on pest management in Red Deer, visit www.reddeer.ca/parks or call the Parks section at 403-342-8234.