CLEARWING MOTHS Integrated Pest Management for Home Gardeners and Landscape Professionals The larvae of several species of clear- wing moths in the insect family Sesiidae are important wood-boring pests in landscapes. Hosts include (actual size) alder, ash, birch, fir, oak, pine, poplar, sycamore, willow, and stone fruit trees such as apricot, cherry, peach, and plum. Larvae that closely re- (actual semble those of clearwing moths in- adult egg size) clude the American plum borer (Euzophera semifuneralis, family (actual Pyralidae), a serious boring pest of size) hosts that include fruit and nut trees, pupa mountain ash, olive, and sycamore. Other common wood-boring pests in landscapes include bark beetles (fam- larvae ily Scolytidae) (for more information, see Pest Notes: Bark Beetles, listed in Suggested Reading), longhorned bor- ers (Cerambycidae), and round- headed borers (Buprestidae). (actual size) IDENTIFICATION Dying limbs, rough or gnarled bark, Figure 1. Clearwing moth stages and life cycle. and sawdustlike frass (insect excre- ment) are good indications that trees wider hind wings. The hind wings, pheromone that attracts males. After are infested with wood-boring in- and in some species the front wings, mating, the female deposits her tiny sects. When clearwing moth larvae are mostly clear. These moths fly dur- reddish to pale pink eggs in cracks, bore beneath tree bark, they push ing the day or at twilight, and their crevices, and rough or wounded areas frass from their tunnels; the frass is yellow and black coloring resembles on bark. Eggs hatch in about 1 to 4 sometimes mixed with gummy tree that of paper wasps or yellowjackets. weeks. The newly emerged larvae exudate. Small piles or a scattered Adults display wasplike behavior by bore into the bark, cambium, or heart- dusting of frass mark the location of intermittently running while rapidly wood of the host tree. Mature larvae tunnel openings. The larvae are 1 to fluttering their wings. They differ in pupate beneath bark, except for the 11/2 inches long at maturity and have color depending on species and sex. peachtree borer, which pupates in a dark brown head and a whitish to They are often yellow, orange, or red soil. The species discussed here have pink body that darkens before pupat- on black or dark blue. one generation per year except for the ing. After larvae mature and pupate western poplar clearwing, which re- and moths emerge, empty brownish LIFE CYCLE quires 1 to 2 years to complete one pupal cases may be observed pro- Clearwing moths develop through generation. truding from bark or on the ground four life stages: egg, larva, pupa, and near the base of the tree. adult (Fig. 1). Adults do not directly At least six species of clearwing moths damage plants and live only about 1 are frequent pests of broadleaf trees Clearwing moth adults have long, week. Soon after emerging from the and shrubs in California and are cov- narrow front wings and shorter, pupal case, female moths emit a ered in this publication. Other com- PEST NOTES Publication 7477 University of California Division of Agriculture and Natural Resources Revised April 2004 April 2004 Clearwing Moths mon species include the sequoia pitch fests red and white ash and also oc- windy weather. Sometimes entire moth (Synanthedon sequoiae) and curs in alder and birch. The adult is trees may die. Other types of wood- Douglas-fir pitch moth (Synanthedon mostly brownish black with an boring insects produce similar novaroensis), which attack pine, orangish red band on the anterior of damage. spruce, and Douglas fir. These coni- the abdomen. Its biology and man- fer-infesting clearwings are discussed agement are similar to those of the MANAGEMENT in Pest Notes: Sequoia Pitch Moth, ash borer. Mature woody plants usually tolerate listed in Suggested Reading. and can recover from the attack of a Sycamore Borer. The sycamore borer, few clearwing moth larvae. However, American Hornet Moth. The Ameri- Synanthedon resplendens, occurs in the the presence of this pest often indi- can hornet moth, Sesia tibialis, closely southwestern United States. It is cates that plants have been injured, resembles the western poplar clear- prevalent in sycamore and also in- stressed, or neglected. Providing trees wing discussed below, and it infests fests oak and ceanothus. The male is with appropriate cultural care is the many of the same plants. Hosts in- mostly yellow with a brownish black primary damage prevention strategy. clude aspen, cottonwood, poplar, and head and black bands on its body. Its Sometimes larvae can be killed by willow. It ranges from New England legs are yellow, except for black puncturing or crushing them. Heavy to the Pacific Coast states. American along the margins on the portions infestations of clearwing moths may hornet moth is mostly blackish blue nearest to the body. The mostly clear warrant treatment with beneficial with some brown, orange, or yellow. wings have orangish to yellow mar- nematodes to kill larvae, broad- gins. Sycamores tolerate extensive spectrum insecticides to kill adults, or Ash Borer. Larvae of the ash borer, boring by this insect, and generally both. Podosesia syringae, also known as the no control is recommended. lilac or lilac-ash borer, mine the wood Traps containing clearwing moth sex of ash, lilac, olive, and privet. This Western Poplar Clearwing. The attractant (pheromone) are used pri- clearwing moth occurs throughout western poplar clearwing, Paran- marily for monitoring. However, con- the United States, but varies in ap- threne robiniae, also called the locust tinual dispersion of clearwing moth pearance and behavior depending on clearwing, is found throughout pheromone throughout the mating location. In the West, the male ash warm, low-elevation areas in the season to reduce the ability of the borer has long brownish legs and a West. In southern California and the adult moth to mate (a process called black body with narrow yellow Central Valley it is a pest of birch, “mating disruption”) has been found bands. In California, ash borer occurs poplar, and willow, usually in effective in reducing peachtree borer primarily in the Central Valley, stressed trees. The adult’s forewings populations and injury in orchards in where it attacks the tree trunks and are an opaque pale orange to brown- the eastern United States. Mating dis- limbs, mostly within about 5 or 10 ish; the hind wings are clear. The ruption is relatively expensive and feet of the ground. Infestations occur thorax is black with a yellow hind labor intensive, and apparently has most often at sites on the tree where border and the abdomen is yellow not been investigated in landscapes. bark has been injured by pruning, with three broad black bands. The improper staking, or previous gen- entire body of the desert form of this Monitoring erations of ash borer. insect is pale yellow. The pale, dark- Because other wood-boring insects headed larvae have two hornlike produce damage resembling that of Peachtree Borer. The peachtree borer, spines on their backs. clearwing moths, correctly identify Synanthedon exitiosa, attacks all stone the cause before taking control action. fruit trees, including apricot, cherry, DAMAGE If insecticide applications are peach, and plum. Adults are mostly Clearwing moth larval feeding can planned, use traps to monitor moth bluish black. Males have narrow yel- cause tree bark to become gnarled or emergence, inspect bark for fresh pu- low bands on their abdomen; females rough. Borer feeding can damage the pal cases, or both. have a single orange band. Virtually all plant’s food- and water-conducting larval tunneling occurs within a few tissues. With some clearwing species Bark Inspection. Immediately before inches of the ground near the base of such as those that attack sycamore adult moths emerge, clearwing pupae the main trunk, after which larvae and pine, feeding is tolerated by trees often force about half of their length emerge and pupate in soil. and apparently causes no serious out of a tunnel and through the sur- harm. Feeding by other species can face of damaged bark. Carefully in- Redbelted Clearwing. The redbelted weaken or kill branches. Branches spect around damaged bark at least clearwing, Synanthedon culiciformis, is weakened by larval tunneling may once each week, starting before adult common around Sacramento. It in- break and fall, especially during emergence is expected. Look for fresh ◆ 2 ◆ April 2004 Clearwing Moths clearwing moth pupal cases protrud- moths for comparison when addi- ing of nematode application (when- ing from bark, in tree crotches, and tional moths are captured. ever borer larvae are feeding) may be around the base of trees. Because old easier to determine than monitoring pupal cases can persist for months, Clearwing moths may be captured in for adults to time trunk sprays. How- remove these when found and moni- traps almost any time during the ever, the quality of nematodes can be tor frequently with care to ensure that growing season. However, each spe- difficult to determine, they can be any pupal cases observed are new. cies typically flies in numbers during difficult to apply effectively, and they This trunk inspection method does only a few weeks or months each can be inconvenient to obtain. not work with peachtree borer be- year. Ash borer and redbelted clear- cause larvae drop from tunnels and wing adults in California fly from Nematodes usually must be mail pupate in soil around tree bases. April through July. Peachtree borer, ordered. They are perishable, so store sycamore borer, and western poplar them as directed (usually under cool, Traps. Traps baited with a phero- clearwing adults are active primarily dark conditions) and do not store mone (insect sex attractant) are avail- from May through July. In southern nematodes for long periods.