LEAFLET in British Columbia by R.W

ISBN 0-662-24685-3 Cat. No. Fo 29-6/70-1996E 70 FOREST Common Insects Damaging Junipers, Pest Cedars1 and Cypresses2 LEAFLET in British Columbia By R.W. Duncan Pacific Forestry Centre Introduction Basic descriptions and life histories are provided to aid in the recognition and control of insects commonly found damaging the following cupressaceous trees: junipers (Juniperus spp.), cedars (Thuja spp.)3, and cypresses (Chamaecyparis spp., Cupressus spp.). Three moths, a scale insect, a bark beetle and a weevil are described: The Cypress Tip Moth, 1 Argyresthia cupressella Walsingham, The Juniper Webworm, 3 Dichomeris marginella (Denis and Fig. 1. Mature cypress tip moth larvae. Schiffermueller), The Cypress Leaftier, 4 Epinotia subviridis Heinrich, Cypress Tip Moth Description The Juniper Scale, 4 Carulaspis juniperi (Bouche), Hosts and distribution Egg: Oblong-oval, about 0.32 mm long and 0.25 mm wide, light yellow. The Redwood Bark Beetle, 5 The cypress tip moth feeds on a wide Phloeosinus sequoiae Hopkins, variety of cupressaceous trees but Larva: 1.4 to 1.7 mm long when The Arbor-Vitae Weevil, 6 most notably on Lawson cypress, newly hatched and 5.2 and 7.0 mm Phyllobius intrusus Kono. Leyland cypress, Monterey cypress, long when mature. Larva (Fig. 1) is Italian cypress, Oriental cedar, and Feeding damage caused by these some species of juniper having scale- insects occurs most frequently on like leaves. 1 Usage in this pest leaflet does not trees in urban areas and includes include Cedrus or Calcocedrus spp. twig and foliage mining, defoliation, This insect is native to western North 2 Usage in this publication does not twig pruning, root pruning, cambium- America and is distributed from include Taxodium or Fitzroya spp boring, and sap sucking resulting in southwest British Columbia to 3 chlorosis of foliage. southern California. Also known as Arbor-vitae. Natural Resources Ressources naturelles Canada Canada Canadian Forest Service canadien Service des forêts Fig. 2. Cypress tip moth adult and cocoon. Fig. 3. Dieback of tip (light-colored area of branchlet). pale greenish yellow when young, crevices between the scale leaves or Damage and detection turning to light green near maturity. in twig crotches. Eggs hatch in about The head and prothoracic shield are three weeks and the larvae bore into Light feeding damage occurs in light brown. nearby scale leaves to feed. After summer and fall when larvae hollow hollowing out a scale leaf, a larva may out and kill individual scale leaves, Pupa: Cylindrical, 3.4 to 4.0 mm move directly into an adjacent scale more severe damage occurs during long and 0.78 to 0.88 mm in diameter, leaf or crawl to a more distant scale. early spring when entire twigs and green, with darker head and Each larva injures 9 to 12 scale leaves branchlets are mined. Repeated appendages. The pupa is enclosed in by autumn; however, this damage is heavy infestations may eliminate any a papery, white, spindle-shaped seldom noticed. The larvae normally apparent growth. Heavily infested cocoon 5.0 to 5.5 mm long and 2.0 to overwinter in the fourth stage, and trees suffer considerable dieback, 2.5 mm wide (Fig. 2). feed only during mild weather. Active imparting a scorched appearance to larval feeding resumes in early spring the foliage. Trees are seldom killed Adult: 8.0 to 9.2 mm wingspan. when each larva bores into a twig 0.3 but their attractiveness is marred. The head is white, the thorax golden to 2.0 cm from the tip and tunnels 0.5 brown, and the abdomen greyish to 2.5 cm down a twig or into a lateral Control white. The forewings are mottled branchlet (Fig. 3). A larva may attack golden brown and creamy white; hind four to six twigs, causing each to die wings are pale grey (Fig. 2). beyond the point of injury. In April or Infestations can be controlled by May, after completing six larval thoroughly spraying the trees in early Life history and habits stages, the mature larva leaves its spring (late March) before serious tunnel, crawls out on the foliage, and damage occurs and following up with spins a cocoon. The pupal stage lasts a repeat application two weeks later. The cypress tip moth flies during May about two weeks. A systemic insecticide should be and June. After mating, the female used. moth lays about 20 eggs singly in 2 Future damage may be prevented by planting less susceptible cupressaceous species such as native western red cedar, Thuja plicata. Juniper Webworm Hosts and distribution The juniper webworm feeds on junipers having needle-like leaves, including common juniper, Chinese juniper, eastern red cedar, and creeping juniper. This insect was introduced from Europe and has since Fig. 5. Juniper webworm — adult (top), pupa (bottom) spread over much of North America. Its range in British Columbia includes the south coast and the southern interior valleys. Adult: A wingspan of approximately As the feeding area increases, 16 mm. The forewings are copper adjacent feeding sites overlap and by Description brown with conspicuous white fall it is common to find three to five margins; the hind wings are grey and larvae in a single large webbed area. heavily fringed. The head and upper Larvae overwinter at various stages of Egg: Subcylindrical with rounded side of the thorax are covered with maturity ranging from fifth to eighth ends, 0.5 by 0.3 mm, white when laid, stiff, white scales (Fig. 5). instar. Following this period of relative changing through yellow and orange inactivity, the larvae then feed to red just before hatching. Life history and habits extensively in April and early May before pupating. The pupal period Larva: 0.5 to 1.0 mm long and lasts about two weeks. yellowish to buff when newly hatched. Adults emerge during May and June. A mature larva is about 12 mm long, After mating, the female lays an Damage and detection light yellowish red with three dark average of 45 eggs, usually singly in reddish brown dorsal lines (Fig. 4). leaf axils on new growth or in bark The head, thoracic shield and legs are crevices. Eggs hatch in 10 to 14 The juniper webworm can cause black. days. A young larva initially mines severe defoliation. Heavily infested needles causing them to turn brown trees may turn completely brown. On Pupa: 6 mm long, dark brown; and die. As the larva grows, it less heavily infested trees, communal usually enclosed by a soft, white constructs a silken tube to nearby nests made up of dead needles, twigs silken cocoon (Fig. 5). needles where it feeds externally. and webbing contrast sharply with the surrounding green foliage. Early signs of infestation often go unnoticed because larvae tend to inhabit the dense, inner parts of the tree. Control This insect can be controlled by spraying the tree with a systemic insecticide. Several species of hymenopterous parasites attack the juniper webworm but do not seem to provide effective control. Fig. 4. Juniper webworm larva. 3 Cypress Leaftier This European introduction is distributed throughout much of North Hosts and distribution America including British Columbia. Description The cypress leaftier feeds on a broad range of cupressaceous trees including cedars, cypresses and Egg: Pink to yellow. junipers. It is distributed on the west coast from southern British Columbia Nymph: A pink to yellow crawler. to California. Adult: The white scale covering the Description female is round and convex, about 1.5 mm in diameter. The scale covering the male is white, elongate with Egg: Disklike and translucent parallel sides and somewhat smaller, white. averaging about 1.0 mm in length (Fig. 7). Larva: Creamy brown changing to Fig. 6. Cypress leaftier larva and feeding- shelter on Chinese juniper. greenish brown when mature; a full Life history and habits size larva is about 10 mm long. Pupa: Brownish pink and about 8 Damage and detection The juniper scale overwinters as a mm long. Pupation occurs in a fertilized female. Up to 40 eggs are tubular silk-lined cocoon attached to a laid during May under the body of the twiglet. The larvae feed near the tips of the female scale. Eggs hatch in about branches, killing branchlets beyond two weeks and the newly emerged Adult: A 16 to 20 mm wingspan. the feeding site. Extensive feeding yellowish crawlers seek new sites on The forewings are checkered with gives the tree a scorched appearance. the same host plant or may be wind alternating light and dark rectangular Feeding shelters are easily seen on blown to other hosts. Once feeding areas; the hind wings are light grey. infested foliage. begins, no further movement occurs. There is one annual generation. Life history and habitats Control Moths emerge from May through July. Thorough spraying of affected trees After mating, eggs are laid singly on from mid-March to early April using a the scale leaves and hatch soon after. systemic insecticide will provide good Newly emerged larvae first bore into a control. twig, after which the larvae emerge and complete most of the larval stage as external feeders on foliage and Juniper Scale twiglets. The larvae construct silken feeding shelters tying together twigs and incorporating frass and gnawed Hosts and distribution leaves (Fig. 6). Larvae may construct several feeding shelters as they move The juniper scale has been recorded to new feeding sites. Most larval on several species within the cypress feeding occurs in early spring from family (Cupressaceae) including: March to April after a winter quiescent Rocky Mountain juniper, common period. Pupation occurs in a feeding juniper, Chinese juniper, eastern red shelter during May and June and lasts cedar, eastern white cedar, Oriental about two weeks.

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