The Douglas-fir tussock moth is a native insect found in low-elevation forests in southern British Columbia. 

The City has trapped and monitored Douglas-fir tussock moth and spruce budworm for the past 15 years to track their presence and activity.

The caterpillars' tiny hairs may also cause skin and eye irritation or allergic reactions in some people. 

Learn more

What you’ll see:

• defoliated Douglas-fir and spruce trees
• cocoons and egg masses on the underside of branches and caterpillars during the summer
• webbing on branches

First, contact the City at 250-828-3461 to report the location of the infestation. This will help our team map and plan for the infestation.

Use a hose to spray the caterpillars, cocoons, and webbing off the tree and dispose of everything in your organics bin. Be careful when handling all material.

The tree is stressed, and sufficient water is important to help the tree recover. Under all drought levels, residents can hand water trees with a spring-loaded nozzle. For more information on watering restrictions during different drought levels, visit Kamloops.ca/Drought.
 

No, not all infested trees will die because of defoliation. A defoliated tree is not necessarily dead. During the Douglas-fir tussock moth and spruce budworm outbreak in Kamloops in 2010, the City treated partially defoliated trees with a natural, bacteria-based biological insecticide control agent. After a couple of years, the trees grew new needles and looked full and healthy.

We encourage residents to hold off on removing infested trees until after bud break in the spring. At that time, you should be able to see if the tree is producing new growth. If the tree doesn’t produce new growth in the spring, it may need to be removed. Contact the City at 250-828-3461 for disposal instructions. Be aware of special disposal instructions if you reside in the Japanese beetle regulated area.

No, an infestation in a tree or a tree that has been partially defoliated does not pose an increase in fire hazard. 

Douglas-fir tussock moths spend the winter as eggs, and the tiny caterpillars emerge in spring. By late July, the caterpillars should have completed the damaging feeding on the tree needles. Next, they cocoon and emerge as moths. The male and female moths mate, with the female laying egg masses on the cocoon she emerged from. The only damaging stage in the life cycle of the Douglas-fir tussock moth is when the larvae hatch in the spring and start feeding on needles. 

Some insecticides are available that will kill the moths now. However, these insecticides are non-selective and will also kill beneficial insects. One of the safest treatments for Douglas-fir tussock moth is aerial application of Btk, a natural, bacteria-based biological insecticide control agent, when the caterpillars first start feeding in the spring.

Important: Do not spray cocoons, egg masses, or moths. Only spray when caterpillars are small to medium size.
 

The City and the BC Ministry of Forests are working together to keep residents informed and determine next steps. Visit the Ministry of Forests website and continue to watch the City’s website and social media channels for updates as they become available.