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Rusty tussock moth

To date, the rusty tussock moth, Orgyia antiqua although collected from several nurseries throughout the province, has been chronic at only one Lower Mainland nursery.

Hosts and damage

Larvae (Figure 104) attack all conifer seedling species. Although usually a pest of container stock (Figure 105), bareroot seedlings have also been damaged. These gregarious caterpillars completely denude a seedling before moving on to the next, and can occur in patches of 5-100 styroblocks.

Life history (Figure 106)

The adult male (Figure 107) is rusty-brown with a white dot and light brown band on each forewing. The female is flightless, sedentary, with light tan hairs covering the body. The population overwinters as white egg masses which can be cemented to the sides and bottoms of styroblocks (Figure 108). They will adhere to the blocks after seedlings have been lifted and blocks washed and stored. Because the eggs are white, they often go unnoticed. Larvae emerge from these egg masses (often on styroblocks) around May, and actively feed on newly emerged seedlings. They are hairy, up to 28 mm long, have two black hair "pencils" projecting forward and one to the rear, four golden brushes of hair on the back, accompanied by eight warty protuberances with yellow and black hairs on each segment. A second generation can appear from mid-July to September.

Management

The large, brightly colored larvae are readily seen and, in small infestations, can be hand-picked and killed. The hairs on the caterpillar's body can cause an itchy welt-like rash (tussockosis) in some people. Large infestations can be controlled by insecticidal sprays.

Selected References
 

Erickson, R.D. 1978. The Douglas-fir tussock moth. Environ. Can., Can. For. Serv. Pac. For. Res. Cent., For. Pest Leafl. 9. Victoria, B.C.

Furniss, R.L. and V.M. Carolin. 1980. Western forest insects, U.S. Dep. Agric For. Serv. Misc. Publ. No. 1339, Washington, D.C.

Summary

Rusty Tussock Moth

Principal, locally grown hosts

Host age and season when damage appears

 

Nursery type and location

 

 

 

     

Bareroot

 

Container

 
 

Age

Season

Coastal

Interior

Coastal

Interior

All species

1+0

Spring through early summer

Yes

No

Yes

No


Figures

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Click on this image for a larger version     Figure 104. Larva (caterpillar) of the rusty tussock moth.

 

 

 

 

 

Click on this image for a larger version     Figure 105. Container-grown spruce with rusty tussock moth feeding damage on needles.

 

 

 

 

Click on this image for a larger version     Figure 106. Life history of rusty tussock moth (one or two generation per year).

 

 

 

 

 

Click on this image for a larger version     Figure 107. Male rusty tussock moth.

 

 

 

 

Click on this image for a larger version     Figure 108. Eggmass of the rusty tussock moth on a styroblock.