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Table: Diagnosis and Control of Red pine shoot moth
Pest Identification Host Plants Damage Symptoms
Red pine shoot moth
Dioryctria resinosella
Red (Norway) pine Scattered dead shoots in the crown of trees. Most attacks are concentrated in the upper crown of open-grown trees. Attacked shoots have a pitch tube and are hollowed out, generally from the middle of the new growth towards the bud end.

This damage can be confused with Diplodia shoot blight.

Heavily attacked trees get a "flattened" appearance to their crown.

Monitoring Control Options Pesticides
Dead shoots become visible in mid-summer. They turn yellow then brown-red in color and many tend to be stunted . Larvae or pupae can be found by cutting open the shoot in early to mid-summer.

If greater than 50% of tunneled shoots have parasites (small wasps) present in mid- to late summer, a population collapse is likely and treatment the following spring should not be required.

This insect should not be viewed as a tree killer and in most cases the damage should be accepted and control not attempted.

Site selection: Avoid planting red pine on drought prone sandy soils, especially as individual specimen trees.

Chemical control: Control can be difficult with any insect that is located inside plant tissue. Timing of treatments should coincide with larval attack on shoots, mid-spring. Treat when shoots are expanded 5-10 cm.

Description and Life History
Description: Larvae can vary greatly in color, ranging from blackish to rosy purple on top and from white to green below. The head and prothoracic shield are brown to black. Length of a full grown larva ranges from 15-18 mm. Pupal cases are about 11-15 mm long and light brown to black in color. Both larvae and pupae are found in the shoots.

Life history: Moths can fly over an extended time, from the mid-June through September. Eggs are laid beneath bark flaps on branches or the main trunk. Egg hatch occurs in late summer and the young larvae construct a silk shelter to overwinter. The following spring larvae bore into developing shoots and cones. Larvae can attack 1-3 cones.

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Last modified on March 06, 2013