Did you Know?A fungus, called blue stain fungus, travels with Ips beetles on a specialized structure on their heads. This mutualistic relationship is beneficial to both parties as the fungus helps the beetle overcome the tree’s natural defenses and the beetle helps the fungus move to new hosts. Talk about a good partnership!
Bark Beetle (Ips)- Tiny holes in trunk
A group of tiny bark beetles that generally affects Spruce, Ponderosa, Pinyon and Austrian Pines. There are 14 known types of Ips beetle in Colorado.
Ips is a very small beetle, measuring 1/8-3/8 inches in length. Often, the identification is found through damage caused by the beetles. Fading and dying tree limbs are the most obvious signs.
Ips begin the year as adults that start to enter trees through the bark when temperatures consistently stay above 50 degrees F. Males enter the tree first and carve out a nice chamber called a “nuptial” where they then release a pheromone to attract females. After mating, the females lay eggs in tunnels that they chew out in Y or H patterns from the main nuptial chamber. These tunnels and the main chamber are cleared of the debris that is often found in mountain pine beetle galleries. The debris is pushed out through the entrance hole and is an indicator of successful attacks because it shows up on the bark or on the ground under the tree, as saw dust or powder.
When the eggs hatch the larvae tunnel further, completing several more growth stages, until they emerge as adult beetles and exit the tree through the bark. This leaves a small round hole (about 1/8″ diameter), also an indicator of beetle presence. They complete 4-7 generations a year. The adults overwinter under the bark or in the shelter of organic matter near the base of trees.
Damage is mechanical. The extensive tunneling by the beetles and larvae girdle the trunks and limbs causing individual limbs and trunks to be cut off from nutrient and water flow, which results in partial and whole tree dieback.
The best prevention of Ips attack is through cultural practices that encourage healthy growth for the trees. This includes proper watering, reduction or prevention of damage and stress, and removal of infested tree debris.
Permethrin is recommended as a protective spray.