The pine tortoise scale, Toumeyella parvicornis, is a major insect pest of pine trees grown as Christmas trees. Pine tortoise scale feeds on many different types of pines, including: Scots, Austrian, and red. Females are 1/6 to 1/4 inches (4.2 to 6.3 mm) in diameter, hemispherical, and red to brown, with dark-brown to black markings. Pine tortoise scales overwinter as fertilized females on branches. Eggs are laid underneath the body of adult females. Females can produce up to 500 eggs within a generation. Eggs hatch and red nymphs (crawlers) are active from late-spring through mid-summer. After finding suitable locations, nymphs will settle down and start feeding. Nymphs can spread to other pines via wind currents or by attaching to birds. Males, like most scale species, develop into winged individuals that fly and mate with females. Males do not feed and eventually die. There is typically one generation of pine tortoise scale per year in Kansas.
Pine tortoise scale feeding results in yellowing of needles, stunted needle growth, and even death of pines under extensive populations. In general, young pine trees are more susceptible to pine tortoise scale than older (mature) trees. In addition, foliage closer to the ground tends to support higher populations of pine tortoise scale than foliage higher in the tree canopy. Pine tortoise scale produces copious amounts of honeydew, a clear sticky liquid that serves as a growing medium for black sooty mold. Entire pine trees may appear blackened from black sooty mold as a consequence of heavy infestations of pine tortoise scale.
A forceful water spray applied twice per week will quickly dislodge/remove the nymphs and mature females from infested pine trees. Insecticides that can be used to suppress populations of pine tortoise scale nymphs include: acephate (Orthene, Bonide Systemic Insect Control), acetamiprid (TriStar; Ortho Flower, Fruit & Vegetable Insect Killer), bifenthrin (Talstar), cyfluthrin (Tempo, BioAdvanced Vegetable & Garden Insect Spray), dinotefuran (Safari), imidacloprid (Merit), insecticidal soap (potassium salts of fatty acids), and horticultural oils (petroleum, mineral or neem-based). These insecticides must be applied when nymphs are present to obtain maximum suppression of pine tortoise scale populations and subsequently alleviate future problems. (Raymond Cloyd)
Pine tortoise scale feeding results in yellowing of needles, stunted needle growth, and even death of pines under extensive populations. In general, young pine trees are more susceptible to pine tortoise scale than older (mature) trees. In addition, foliage closer to the ground tends to support higher populations of pine tortoise scale than foliage higher in the tree canopy. Pine tortoise scale produces copious amounts of honeydew, a clear sticky liquid that serves as a growing medium for black sooty mold. Entire pine trees may appear blackened from black sooty mold as a consequence of heavy infestations of pine tortoise scale.
A forceful water spray applied twice per week will quickly dislodge/remove the nymphs and mature females from infested pine trees. Insecticides that can be used to suppress populations of pine tortoise scale nymphs include: acephate (Orthene, Bonide Systemic Insect Control), acetamiprid (TriStar; Ortho Flower, Fruit & Vegetable Insect Killer), bifenthrin (Talstar), cyfluthrin (Tempo, BioAdvanced Vegetable & Garden Insect Spray), dinotefuran (Safari), imidacloprid (Merit), insecticidal soap (potassium salts of fatty acids), and horticultural oils (petroleum, mineral or neem-based). These insecticides must be applied when nymphs are present to obtain maximum suppression of pine tortoise scale populations and subsequently alleviate future problems. (Raymond Cloyd)
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