Woolly Pine Scale Stephen R

Forest Insect & Disease Leaflet 178 December 2010 U.S. Department of Agriculture • Forest Service Woolly Pine Scale Stephen R. Clarke1 The woolly pine scale, Pseudophilippia quaintancii Cockerell, is a soft scale insect (Heteroptera: Coccidae) which infests pines in the southeastern United States. The woolly pine scale generally is not considered economically important in forest environments, but problems may occur in areas receiving insecticide treatments, including seed orchards, Christmas tree pine (P. mugo Turra), table mountain plantations, and ornamental plantings. pine (P. pungens Lamb.), and Woolly pine scales are often found Caribbean pine (P. caribaea Morelet). cohabiting the shoots with the striped Infestations have been found only in pine scale, Toumeyella pini (King), the eastern United States from New the pine tortoise scale, T. parvicornis York to Florida and west to Louisiana. (Cockerell), and a mealybug, Oracella Though host pines occur in Texas, acuta (Lobdell). there have been no reports of woolly pine scale infestations. Range and Host Trees The recorded hosts of the woolly pine Life History and Description scale are loblolly pine (Pinus taeda The woolly pine scale has two L.), slash pine (P. elliottii Engelm. var. generations per year. Overwintered elliottii), shortleaf pine (P. echinata females at the shoot tip begin Cockerell), longleaf pine (P. palustris oviposition when the first cycle of Mill.), pitch pine (P. rigida Mill.), shoot elongation begins. The eggs sand pine (P. clausa (Chapm.)), mugo 1Forest Entomologist, USDA Forest Service, Forest Health Protection, Southern Region, Lufkin, TX hatch almost immediately, and the first covering called a test. First generation instars, known as crawlers, emerge. adult males are wingless, brown, and The crawlers are the mobile stage, and have a short, pointed aedeagus, or sex have six legs. They are small with an organ (Figure 3). They are smaller elongate oval shape, and are yellow to than the mature females and are most red in color. First generation crawlers often observed trapped in the woolly quickly settle on the new growth, covering of the females. covering the shoot above the parent female. The settled scale insects begin Females begin egg production around secreting a white wax covering almost one week after mating. It is unknown immediately, giving the new shoot a if unmated females will produce woolly appearance (Figure 1). viable eggs. Oviposition lasts from mid-May through June in south Females have four instars. Once Georgia, and occurs several weeks settled, the females do not move, as later in the northern parts of the range. their legs become greatly reduced Dispersal takes place in the second after the crawler stage. Second instar generation, as there is little or no females are small, yellowish, and oval room on the infested shoots for female (Figure 2), but adults become plump crawlers to settle. The female crawlers and circular when swollen with eggs, are blown by the wind or crawl to and their exoskeleton hardens and uninfested new shoot growth to settle. turns dark brown. A majority of the It is possible that crawlers are carried first generation scales are females, by other insects or animals to new but a few males are also produced, host trees. Second generation females settling among the females on the new generally settle at the shoot tip and growth. initially can be detected by their woolly secretions. The males have five instars, including a prepupal and pupal stage. Males A large number of second generation develop within an elongate, waxy males are also produced, and first instar males crawl directly down the shoot and settle near the base of the previous year’s needles. Woolly pine scale infestations are easily recognizable during the second generation, as the males on the old needles secrete copious amounts of woolly wax (Figure 4), giving the tree a flocculent Figure 1. First generation females on a pine shoot. 2 appearance (Figure 5). The adult males emerge after several weeks. Emergence peaks in early July in south Georgia and is 3-3 1/2 weeks later farther north. The second generation males are winged (Figure 6), and fly to dispersed females Figure 2. Recently settled female woolly pine scale. to mate. Males of both generations a sweet, sticky substance which will mate with multiple females. provides a growth medium for sooty mold fungi. Sooty mold growth, The second generation females appear coupled with the waxy secretions to remain dormant until the following produced by the scales, may retard spring. Their woolly covering often photosynthetic activity and lead to disappears during the fall and winter, reduced tree growth. The honeydew and survivors are difficult to detect. also attracts bees, ants, and wasps Mortality rates of females during the which can become a nuisance to extended second generation can reach orchard workers or homeowners. 85 percent. Natural Enemies Damage The woolly pine scale shares natural Damage by the woolly pine scale is enemies with other soft scales of mostly cosmetic, though heavy populations may cause stunted shoot growth. The scales are sucking insects, and the removal of the sap from feeding on both the shoots and needles may weaken or stress the tree. The scales also produce honeydew, Figure 3. Wingless, first generation male. 3 Figure 4. Second generation males on older needles beneath first generation females on new growth. southern pines, including the striped generally the application of pesticides pine scale and the pine tortoise to control other species, disrupts the scale. Predators of the woolly pine normal host-natural enemy balance. scale include green lacewings, Insecticide applications may decimate Chrysopa spp., and a pyralid larva, the mobile parasites and predators, Laetilia coccidivora (Comstock). The while adult scale insects are often identified parasitoids are an aphelinid, unaffected due to their sedentary Coccophagus lycimnia Walker,and an nature and the position of the spiracles encyrtid, Metaphycus sp. and feeding stylets beneath the body. Woolly pine scales are further Causes of Outbreaks protected from the sprays by their wax secretions. The use of pyrethroid Woolly pine scales are secondary insecticides in particular appears pests, and populations normally occur to lead to scale insect outbreaks on at non-damaging levels. Though it is southern pines, and aerial applications assumed that natural enemies help are more likely to fuel infestations prevent woolly pine scale outbreaks in than ground applications. During southern pine forests, it is unknown outbreaks, the reported parasitism which species are the most important rates of the woolly pine scale were in regulating populations at low levels. under 5%, lending credence to the disruption of the natural enemies as a Woolly pine scales usually attain major factor in population eruptions. pest status only after some factor, 4 Figure 5. Pine infested by woolly pine scale. Woolly pine scale outbreaks often generations per year, and outbreaks appear as delayed problems, occurring can occur rapidly. one or two years after the initiation of insecticide treatments. This apparent Fertilization, irrigation, and even delay may be due to the fact that there insecticide application have been are only two generations per year, shown to increase egg production therefore population numbers take of scale insects, but their effects time to increase. Other secondary on woolly pine scale fecundity are pests in southern pines may have 4-5 unknown. Climatic conditions that favor increased survival, especially of dispersing second generation males and females, may be a factor in population increases. The woolly pine scale only has two generations per year throughout its range, so increased temperatures do not result in increased numbers of their Figure 6 Second generation males. 5 generations. However, warmer pine scale insects than pyrethroid temperatures for extended periods insecticides, but these broad spectrum of time could increase the number insecticides have greater negative of generations and activity of their impacts on beneficial natural enemies. natural enemies, leading to quicker woolly pine scale population declines. Heavy, drenching sprays of insecticides may kill adults, but Management this technique is not advised due to incomplete control of the scale insects, No control is generally recommended treatment costs, environmental for woolly pine scale infestations. hazards, and the potential for future Outbreaks are substantially reduced pest problems. Horticultural oils by natural enemies and perhaps also can be applied to suppress environmental factors after one to two adult populations, and have fewer years if left untreated by insecticides. negative consequences for non-target If spraying is necessary to control organisms. Systemic insecticides other pests, insecticides should be applied as a soil drench around the selected which have little residual base of the tree may be an option for activity and are the least toxic to the infested ornamental pines. Consult a natural enemy population. Ground local agricultural or forestry extension applications should be favored over agent for recommendations on which aerial spraying, and treatments type of oil or systemic insecticide to should be scheduled during periods of use and when to apply. crawler activity when feasible. If severe infestations occur, insecticidal treatments against wooly pine scales may become desirable. Applications should coincide with crawler

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