The European pine shoot moth (Rhyacionia buoliana) is an established pest in landscape, Christmas tree, and nursery pine plantings in western Washington. The shoot moth stunts and deforms pines so that symmetry is lost. As a result, damaged pines are no longer suitable for Christmas trees, nursery stock, or landscaping purposes.
The European pine shoot moth was first found in 1959 in King County. Since then, it has spread to other areas. So far, serious infestations have been confined to ornamental plantings, except for some native lodgepole and shore pine plantings.Damage
Buds or shoots with large pitch globules are evidence of attack. Distorted or dying shoots are often evident if the moth is abundant. Damage to buds can be detected throughout the winter. Damage to new shoots is noticeable in late spring or early summer. New infestations first appear as tents made of pitch and silk on buds. Old injury may occur as bushy growth on leaders and ends of lateral branches, forking of the leader, tree stunting, or the presence of dead, curled shoots (this condition is known as "shepherd's crooking").
Shoot moth damage to buds.Description
The larvae are the damaging stage. They are small, hairless, and brown with black heads. When fully grown, they are about 3/4 inch long. After hatching, the larvae bore into needle sheaths and feed for a time before boring into the buds. This insect overwinters as young larvae found either within buds or under resin masses on the buds. In spring, the larvae leave the buds and attack uninfested buds or expanding shoots.European pine shoot moth adult.
European pine shoot moth larva.In May and June, the larvae change into pupae, which wiggle part way out of the infested shoot before emerging as adults 2 or 3 weeks later. Empty pupal skins sticking out of dead shoots are reliable evidence of infestation.
Adult moths usually begin emerging in late May and continue until mid-July, with peak emergence in June. They are orange-brown with silvery markings and have a wing spread of 3/4 inch. They lay single eggs or small clusters of yellowish disc-shaped eggs on needles near the ends of branches.Control
Several pesticides are registered for control of this pest. Since pesticide registrations are not permanent and sometimes change faster than we'd like, they are not listed here. Look for pesticides registered for this pest in the Pacific Northwest Insect Control Handbook, which is revised annually. If your library does not carry this publication, you can request the information through WSU plant clinics, county extension agents, entomology specialists, or through WSU Master Gardener clinics.
The beginning spray date of June 1 is based on predicting the date for the first application through monitoring experiments. This has been done only for the Puyallup area, where dates have varied from May 25 to June 13. In all likelihood, dates vary geographically as well. Satisfactory prediction, resulting in good control, can be achieved by any one of the following three methods:
1. Monitor Pupation. First flight occurs when the
total population reaches 80% pupae versus 20%
larvae. A weekly sample of 100 infested buds, be-
ginning about May 1, is adequate for this determi-
nation. Make a graph and plot percent pupation
for each weekly observation; then extend the line
to 80% pupation. That calculated date is the pre-
dicted date to begin pesticide application. For more
precision, increase the frequency of sampling
after mid-May.
2. Use Sex Lure Traps. The sex lure (pheromone)
trapping method is effective for determining first
flight. Place baited traps in or near pines that you
intend to protect. Examine them every few days
from mid-May on to determine the time to make
the first application. When the first moth is caught
it is time to spray, so be prepared to go on short
notice. Commercial growers interested in using
these traps may contact the authors for informa-
tion on where to get them.
3. Keep Temperature Records. This method involves
some calculation but has the advantage of enabling
prediction from a site at any distance from the plan-
tation, provided there is a means for obtaining daily
maximum and minimum temperatures from a site
near the plantation (or a site with climatic condi-
tions similar to those at the plantation). The pro-
jected time of first European pine shoot moth emer-
gence is 711± 10-day degrees (Fahrenheit) after
April 1. Day degrees are calculated by averaging
the daily maximum and minimum temperatures
and subtracting 40 degrees. Negative figures are
recorded as 0.
Accumulation of these daily day degrees will increase with the progression of the season and allow one to project when 711 will be reached.
Prepared by
A.L. Antonelli, Ph.D., Washington Sate University Cooperative Extension Entomologist, WSU Puyallup.
Use pesticides with care. Apply them only to plants, animals, or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.
College of Agriculture and Home Economics
Washington State University Cooperative Extension bulletins contain material written and produced for public distribution. You may reprint written material, provided you do not use it to endorse a commercial product. Please reference by title and credit Washington State University Cooperative Extension.
Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Evidence of noncompliance may be reported through your local Cooperative Extension office. Trade names have been used to simplify information; no endorsement is intended. Revised September 1995. Subject Code 255. A
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