PINE TORTOISE SCALE ( Toumeyella parvicornis )
The Pine tortoise scale, gets its name from the characteristic appearance of the mature females. They look like tiny tortoises up to 1/4 inch in diameter and are most often found on 1- and 2-year-old shoots of "hard" pines. Scots pine and jack pine are the two species most severely attacked by pine tortoise scales, but red and Austrian pines are also affected.
Pine tortoise scale insects overwinter on host twigs as immature females. They are reddish brown and slightly wrinkled, but shiny, when they first begin to develop on the twigs. The females resume growth in the spring, reaching maturity in June. The, eggs are laid beneath the female's body (up to 500 per female!) and the amber-colored young scale crawlers begin to emerge in late June or early July. Males will die after mating, while females will develop until the cold temperatures of autumn force them into dormancy. These insects also produce honeydew, a substrate for the growth of a sooty mold fungus that blackens affected plants.
Pine tortoise shell scale infestations occur sporadically, and small populations are tolerable. However, as trees mature and their crowns begin to intermingle, opportunities for scale crawlers to spread to adjacent trees increase as do chances for more serious problems including reduced tree quality from feeding damage and sooty mold growth. Use a registered insecticide to control the tiny amber crawlers when they emerge in late June, (around 618-1050 GDD), and you see them on the needles. If trees are so badly infested that disposal seems to be the most logical option, do NOT drag trees out of the plantation between mid-June and late-July. That is when crawlers are most likely to be active and your efforts to reduce insect damage could actually spread the crawlers over a greater area.
Fig. 1. Here the helmet-shaped pine tortoise scale adults are found in large numbers on a pine branch. This branch is dark from the sooty mold which grows on the scale exudate.
Fig. 2. This closeup of some adult scales also shows some of the tiny yellowish crawlers, just visible on the needles above the scale, on the left side of the photograph.
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