Peleg BA, 1989. Apply horticultural oils in late fall and early spring to smother overwintering nymphs. The eggs hatch into pale yellow-green crawlers in late June or July and migrat… Alon Hanotea, 43(6):681-686. Statewide IPM Program, Agriculture and Natural Resources, University of California Cottony cushion scale crawlers. Natural predators such as various species of lady beetles feed on the immature scales situated on the leaves. Mature females are pale to dark brown, convex, and about 3-6 mm long (Fig. Figure 7. Other species of wax scales include tree dwellers like the cottony maple scale (Pulvinaria innumerabilis) or the calico scale … Their eggs are white to pale yellow and are meshed in a white, cottony ovisac which may be up to 5mm wide and 12mm long. If scales can’t be tolerated, apply narrow range horticultural oil to deciduous hosts during the dormant season or spray foliage with insecticides when the females are dead and the tiny reddish scale crawlers and younger instars are infesting the leaves (spring or fall). Cottony cushion scale outbreaks have been observed following use of this insecticide because the vedalia beetles were removed and the insecticide didn’t control the pest. In order to increase in size, scales shed their outer skin (molt) and grow a new, larger covering. If scale populations are heavy enough the tree may show twig and limb dieback as the insect spends the winter on the twigs once the leaves drop off. Oakland: Univ. The European fruit lecanium scale is the most common soft scale in Utah. By late May or early June the female scale has matured and begins to lay hundreds of eggs within a white frothy wax. The cottony maple scale is common on maple, boxelder, hackberry, dogwood, beech, apple, oak, linden, honeylocust, and elm. Accessibility   This red and black lady beetle was introduced from Australia in the 1890s and saved California’s fledgling citrus industry from destruction by these prolific scales. In some cases, premature leaf drop may also occur due to scale feeding. All contents copyright © The scale overwinters as an immature female on the twigs of the host. Its cottony egg sac and profuse honeydew production make cottony cushion scale easy to spot in the landscape. Figure 4. You can use traps made of double-sided sticky tape to determine when crawlers are hatching. Protect young or sensitive trunks, especially citrus, from possible injury by wrapping the trunk with a collar of duct tape or fabric tree wrap and coating this with the sticky material. Cottony Maple Scale Pulvinaria innumerabilis. Crawler or first nymph stage, of the cottony cushion scale, Icerya purchasi. Mature larvae (Figure 10) and adult beetles feed on all scale stages. A dormant oil spray applied to the trunk and branches of the tree may also be used to reduce overwintering female populations and eliminate the risk of killing off beneficial insects such as lady beetles and parasites. To make matters worse, imidacloprid is very toxic to vedalia beetles. Scales attain a maximum length of about 0.25 inch during spring. This is best applied when the scale are in their younger nymph stages, so make sure to regularly check your landscape for pests. Spray treatment for crawler stage: Cottony cushion scale (Icerya purchasi) is a scale insect that feeds on many woody plants and is particularly fond of citrus.The mature insects lay white, squishy egg sacs containing hundreds of red eggs on twigs and branches. Contact UC IPM, Agriculture and Natural Resources, University of California, © 2019 Regents of the University of California Second-instar nymphs settle on twigs and leaves, usually along leaf veins (Figure 5). After four molts, the larvae pupate inside the scale. The beetles are poisoned when they feed on cottony cushion scale that have ingested imidacloprid. Insect Problems: Cottony maple scale, Pulvinaria innumerabilis. Calif. Agric. Both of these materials can be quite toxic to natural enemies, honey bees, and nontarget organisms; acephate is allowed only for use on ornamentals. They are slightly convex and are brown with a yellow-brown ridge down the back . A mature female cottony maple scale is 1/8" long, and has a brown, flat, oval body. Staff-only pages Common hosts in California are citrus, cocculus, nandina, and pittosporum. The cottony maple scale and the European fruit lecanium scale are two of the more common scales in our area (Figure 1). Coffee scale is a major agricultural pest in coffee crops. The life cycle of the Cryptochaetum fly is about four weeks in warm weather. Maple cotton scale is found on several other common hardwood trees such as ash, elm and boxelder. Produced by University of California Statewide IPM Program. Nymphs of the cottony cushion scale, Icerya purchasi. Figure 5. Pest description and crop damage This scale overwinters on grape canes as an immature brownish to black scale of about 0.06 to 0.14 inch long and has a flat and oval outline. Nonchemical Control There are a number of natural enemies of the cottony maple scale including a number of wasp and fly parasites. Severely prune back heavily infested branches and protect new growth with insecticide applications. Figure 8. Immature scales look reddish for a short period of time before they begin producing more cottony secretions. Scientific Name. Inspect female scales for Cryptochaetum emergence holes. Adult female beetles lay their oblong red eggs underneath the female scale or attached to her egg sac. The fourth, and last, larval instar stops feeding, crawls toward the outside of the tree, and attaches its posterior end to a leaf in preparation for pupation. maple, sweet gum, tuliptree and ornamental fruit trees. Damage Symptoms: Calico scale covers the branches and leaves of the host plant and feeds on the phloem tissue. What people most often notice is the reddish brown protective cover of the adult female scale; on the cottony maple scale, the covering puffs out as the “cotton” becomes visible. Eggs masses are conspicuously white and cottony in appearance. Imidacloprid controls European elm scale and most soft scales but does not control … Alternatively, pesticide baits such as ant stakes may be placed near nests or on ant trails beneath plants. Homes, Gardens, Landscapes, and Turf > Barkis usually intact beneath a scale. ... Commercial examples include: pyrethroids, dinotefuran, imidacloprid, buprofezin, spirotetramat, and more The cottony maple scale is most easily recognized by the characteristic egg masses on twigs and branches. Each time a scale molts, it leaves behind its white, cottony molting skin. Cottony cushion scale has two to three generations a year. PDF reader. Contact webmaster. Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, 2nd ed. Description The overwintering form of the cottony maple scale is a small, brown, flattened 1/8 inch long scale attached to the bark of twigs and small branches. Once eggs begin hatching, scale crawlers get stuck on the tape and appear as red or orange specks. Colony of cottony cushion scale. However, over-fertilization favors scale buildup. PDF: To display a PDF document, you may need to use a Res. The scale overwinters as an immature female on the twigs of the host. Mature cottony cushion scale females on bark. The beetles are poisoned when they feed on cottony cushion scale that have ingested imidacloprid. Male scales are tiny, winged insects. Calif. Agric. Life History The cottony maple scale is common on maple, boxelder, hackberry, dogwood, beech, apple, oak, linden, honeylocust, and elm. Cottony cushion scale is usually well controlled by two introduced natural enemies. Outbreaks generally buildup over a period of years and then disappear due to natural enemies and climatic factors. The plant may be covered in sooty mold as a result of the large quantities of honeydew produced by the calico scale. Cottony maple scale infestations are usually controlled by natural enemies and do not usually need to be managed. Cottony cushion scale second-instar nymphs. By late spring the insect has developed into a mature female and begins laying as many as 1,000 eggs. If you find evidence of these natural enemies, then insecticide treatments aren’t necessary. Adult cottony cushion scale female with an adult vedalia beetle in the foreground and vedalia beetle nymphs and eggs on its back. Infestations are most easily noticed during the summer when females produce white, cottony egg sacs that resemble pieces of popcorn on a twigs. This honeydew is readily colonized by sooty mold fungi which will result in a blackened appearance to leaves, twigs, and branches. Feeding by the scales may result in heavy concentrations of honeydew. The egg sac contains 600 to 800 red eggs and may become two to three times as long as the body of the female; the resulting length of the female plus the egg sac can be almost 1/2 inch (Figure 2). Feeding can result in defoliation and dieback of twigs and small branches when infestations are extremely heavy (Figure 7). Cottony cushion scale, Icerya purchasi, can infest a number of woody ornamentals and certain crops (Figure 1). The most famous one is the vedalia beetle, Rodolia cardinalis,(Figure 9). Natural enemies are the best method for controlling cottony cushion scale, so look carefully for their presence and avoid insecticides if you find evidence of natural enemies attacking cottony cushion scale. Common Name. For example, acetamiprid (Ortho Flower, Fruit & Vegetable Insect Killer) controls soft scales but is not very effective on armored scales and can only be applied by spraying foliage. Conserve natural enemies of cottony cushion scale by controlling ants and dust and by avoiding the use of persistent insecticides. Well established and vigorously growing trees are usually able overcome the infestation. Check the sticky material every week or two and stir it with a stick to prevent the material from becoming covered with debris that ants can cross. Both scales produce white, cottony ovisacs, and both have wide host ranges; however, as its common name implies, cottony maple leaf scale produces its ovisacs on the underside of its host's leaves. Nat. Each mass usually contains 1,000-1,500 eggs. It is also known to be able to survive on other deciduous trees and shrubs including honey and black locust, white ash, euonymus, oak, boxelder, dogwood, hackberry, sycamore, linden, beech, elm, willow, basswood, poplar, rose and sumac. Like other scales, cottony cushion scale decreases the vitality of its host by sucking phloem sap from the leaves, twigs, branches, and trunk. Mature vedalia beetle larva feeding on cottony cushion scale. Nat. During the summer, the scale enlarges by secreting wax resulting in a body several times greater than the overwintering form. Figure 12. The adult female beetle lays eggs underneath the scale or attached to scale egg sacs. Consequently, they may not be effective where several … By late spring the insect has developed into a mature female and begins laying as many as 1,000 eggs. If practical, improve plant sites to reduce stress and promote growth. 2004. Both the vedalia beetle and Cryptochaetum are active in coastal areas; the vedalia beetle is also abundant in Southern California desert regions and is the predominant species in interior areas of California. Cottony cushion scale, citrus fluted scale. The most common scale insects that infest maple trees are the armored varieties oystershell scale and scurfy scale, as well as the soft varieties cottony maple scale and lecanium scale. The males die within a few days after mating as they are unable to feed. Before crawlers begin to emerge in spring, tightly encircle several twigs or branches near adult female scale with transparent tape that is sticky on both sides, such as Scotch double-sided tape. Horticultural oil can also be applied to manage the crawler stage and is least disruptive of natural enemies or bees. Cottony Maple Scale on Silver Maple Leaf. Cottony maple scale (on silver maples and honeylocust) and severval Lecanium scale spp. In extreme cases, it is possible to lose the tree. Immature females are flat and inconspicuous. An exception is on Cocculus laurifolius (laurel-leaf snailseed or laurel leaf cocculus); it is often highly infested with cottony cushion scale, especially when grown away from the coast, because scale-feeding vedalia beetles avoid this plant. For additional photographs of each life stage of cottony cushion scale, consult Stages of the Cottony Cushion Scale (Icerya purchasi) and its Natural Enemy, the Vedalia Beetle (Rodolia cardinalis). Adult parasitic fly Cryptochaetum iceryae (left) and female cottony cushion scales with parasite emergence holes (right). A few of the species that fall into the armored scales are oystershell scale, San Jose scale, euonymus scale, and pine needle scale. Click on image for larger version Figure 2. Reddish beetle pupae develop within the grayish skin of the last larval instar (Figure 11). Calif. Agric. Do not apply imidacloprid (Merit or Bayer Advanced Citrus Fruit and Vegetables) for cottony cushion scale control. Heavy populations can severely reduce the yield of citrus trees. Cottony cushion scale outbreaks have been observed following use of this insecticide because the vedalia beetles were removed and the insecticide didn’t control the pest. When honeydew falls from a tree, leaves shouldbe inspected for live soft scales or mealybugs. Evaluation of the insect growth regulator pyriproxyfen (Tiger) as a control agent for the California red scale and the cottony-cushion scale. Eggs hatch into crawlers (Figure 3) in a few days during warm weather but take up to two months to hatch in winter. and many others) have a similar life cycle to the calico scale. In large numbers, feeding can result in branch dieback. 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