The larvae of this insect look like a caterpillar. They eat the needles of Spruce causing damage. They have yellowish bodies and yellow/brown heads. The new needles are attacked first. They are chewed down almost to the base before the insect moves on to older needles. A severe infestation, lasting for 3 or more years can kill a tree due to the foliage loss and lack of photosynthetic energy being created.
Photo by: Steven Katovich, Bugwood.org
Key Points
- When in the larvae stage these insects feed on needles starting with the youngest and then moving on to older growth.
- A severe infestation, lasting for 3 or more years can kill a tree due to the foliage loss and lack of photosynthetic energy being created.
- Non chemical controls like high pressure water spray or picking off by hand can be very effective.
- Chemical spray in early July is also available
Tree Damage
- Needles are chewed by the larvae. Usually starting on the lower limbs of the tree around the end of June or early July in Calgary.
- The youngest needles (at the tips of branches) are generally attacked first before the insect moves on to the older growth.
- Trees with an infestation over a period of 2 or more years will show obvious defoliation.
Control Measures
- Inspect trees annually for signs of damage or larvae.
- It is possible to remove the larvae by hand if it’s a low level infestation.
- A high-pressure spray of water will effectively remove most of the larvae.
- A professional pesticide applicator can apply the high pressure water or a mild pesticide on large scale infestations or when the scope is beyond your means.
