The Colorado blue spruce is a popular type of Christmas tree, with people often choosing it as a living Christmas tree so they may plant it afterwards on their property. The tree is the state tree of Utah as well as Colorado and in the wild may exceed 100 feet in height. If you feel that a Colorado blue spruce would be a good fit for your landscape, you should acquaint yourself with some of the more common insect pests that can afflict it.
This type of spruce tree possesses a deep root system, so once established it can withstand high winds that would knock down other species. It can grow in the shade and does well in rich soil. In the wild, it will grow along streams and rivers, preferring places where there is ample moisture in the ground. The needles have a bluish color that makes the tree quite attractive and as it grows, it takes on the shape of a pyramid, with a crown that looks like a cone. Colorado blue spruce can live between 600 and 800 years under ideal conditions.
One pest of the Colorado blue spruce is the spruce budworm. This moth will lay its eggs in a spruce tree's branches, where they hatch in as little as ten days. Upon hatching, these caterpillars will not eat anything, but rather they seek crevices in the spruce's bark and twigs where they quickly spin a home of silk where they stay through the winter and into the spring. Once it becomes warm enough, typically in May, the caterpillar emerges from its hideout and then attacks the buds of the spruce tree. They change into the adult moth after a short pupal stage in June and July and start the cycle over, laying their own eggs on other spruces.
Some of the effects these blue spruce pests have on their host tree are accumulative, adding up year after year until the tree begins to suffer. The spruce budworm, for example, can kill a tree if it defoliates it severely. Your younger spruces will have reduced growth from the budworm eating the new buds and if it keeps afflicting the tree, the spruce can die.
The spruce bark beetle is a serious pest of the Colorado blue spruce, capable of destroying the tree as its larvae will bore into the bark, damaging the wood and eventually killing the spruce. It has a very wide geographic range, existing from as far to the east as Maine in the U.S. and Newfoundland in Canada. Its range extends from there through the North to the western states as far as Northern California, with pockets of the bugs found in the Rocky Mountains. In Canada, the range goes to the Pacific Ocean and as far north as the tundra; Eastern Alaska has this pest according to the U.S. Department of Agriculture Forest Service website.
The spider mite is another potential problem for your blue spruce. These are not spiders, but they are not insects either, belonging to the arachnid family the same as ticks and spiders. You will have a difficult time detecting them, as the females, which are the bigger of the sexes, are barely a twentieth of an inch in length. Pests of many types of plants, the spider mites form colonies and can overwhelm a spruce tree by sucking the juices from the needles. You might require a magnifying glass to see them at their work.