Pine tortoise scale

Distribution

Eastern Canada, Prairie Provinces

Micro-habitat(s)

Twig, Branch, Annual shoot

Damage, symptoms and biology

Pine tortoise scale larvae cause yellowing of the needles, and reddening and mortality of the twigs. The honeydew and frass left by the female on the twigs are eventually covered by sooty mold (black fungus), giving the branches a blackish appearance.

The newly hatched larvae begin feeding on young shoots, sucking the sap from the twigs. They produce a waxy protective substance. Adult females can be detected in groups on twigs by the presence of their brick-red, hard, shell-like covers. In the spring, the eggs are laid and develop beneath this cover.

Although pine tortoise scale prefers small trees, it sometimes feeds on larger pines. A severe infestation can result in branch mortality and even the death of the entire tree.

In pine tortoise scale, only the young larvae, or crawlers, are mobile. They eventually become fixed to feeding sites on annual shoots, after which they are no longer mobile. Male and female scales develop differently: the cover of the male is long and whitish in colour. They have a pupal stage and the adults are winged. The cover of the females is rounded and brick-red in colour. Immature females mate, continue their development until late fall and overwinter at this stage. The pine tortoise scale has one generation per year.

Life cycle (East of the Rockies)

Other information

Pine tortoise scale was first reported in 1920 in the state of Wisconsin, in the United States. Since then, it has also been reported in Canada. Infestations of this insect are generally localized, but can be severe.

To limit damage, it is recommended that the affected part of the host tree be pruned out and destroyed. The presence of predatory larvae of the lady beetle family contributes to controlling pine tortoise scale invasions.

Main host(s)

Jack pine, scots pine