Forest Insect

& Disease

Leaflet 185

April 2017

U.S. Department of Agriculture • Forest Service

Sequoia Pitch Moth

Constance J. Mehmel1 and Christine Buhl2

According to an early report by 

Edwards, the species was “devastating 

the pine forests in Mendocino 

County, California, and is particularly 

destructive to the big-tree (Sequoia 

sempervirens)...” Despite this early 

report, sequoia pitch moth is not known 

to feed on sequoia species. 

Introduction

Sequoia pitch moth, Synanthedon 

sequoiae Hy. Edwards, is one of two 

clearwing moths (order Lepidoptera; 

family Sesiidae) that infest conifers 

in western North America. Sequoia 

pitch moth larvae feed on the phloem 

of many species of pines, and may 

occasionally attack Douglas-fi r and 

spruce. Large-scale outbreaks in forest 

settings are not known to occur, but 

sequoia pitch moth can be a serious 

problem in seed orchards. Non-native 

and off-site pines are at high risk 

of attack. Sequoia pitch moth can 

be a damaging pest of ornamental 

plantings and tree improvement 

plantations where trees originate from 

many different seed sources. Sequoia 

pitch moth occurs from central British 

Columbia to California and east to 

Idaho and Montana (Figure 1).

The fi rst report of this species was 

provided by Henry Edwards in 

1881. It was originally placed in the 

genus Bembecia, then Aegeria and 

later Vespamima, all now defunct. 

1

Forest Entomologist, U.S. Department of Agriculture, Forest Service, OkanoganWenatchee National Forest, Pacifi c Northwest Region, Wenatchee, Washington. 

2

Forest Entomologist, Oregon Department of Forestry, Forest Health, Salem, Oregon. 

Figure 1 – Distribution of sequoia pitch moth 

(Synanthedon sequoiae)
2

Another clearwing moth, the Douglasfi r pitch moth (S. novaroensis), infests 

Douglas-fi r, Sitka spruce, Engelmann 

spruce, western white pine, ponderosa 

pine and lodgepole pine. It is similar to 

sequoia pitch moth in its appearance, 

distribution and habits. However, 

the abdomen of the Douglas-fi r pitch 

moth has a mostly orange (rather than 

yellow) ventral surface and orange 

bands (rather than yellow bands) 

across the dorsal surface.

The only other clearwing moth in 

North America known to feed on hosts 

in the family Pinaceae is the pitch mass 

borer (S. pini). This insect is similar 

in appearance to the Douglas-fi r pitch 

moth. It is not known to occur in the 

west, but ranges from southeastern 

Canada, south along the Atlantic 

Coast, the Appalachians and the 

Midwest, largely following the range 

of its principal host, eastern white pine 

(Pinus strobus). 

Description

Clearwing moths strongly mimic bees 

and wasps in general appearance and 

behavior. The adult sequoia pitch moth 

superfi cially resembles a yellowjacket 

wasp in color and size (Figure 2). It 

has narrow wings devoid of scales 

similar to the membranous wings of 

wasps. Adults are capable of rapid 

fl ight facilitated by the interlocking 

of fore and hind wings. The head and 

thorax are black with yellow markings 

and the abdomen is black with yellow 

bands. Width of the bands is variable, 

with some adults predominantly 

yellow, others predominantly black. 

Adults are about 3⁄4” long with a 

wingspan of 3⁄4” to 13⁄4”. Both sexes 

are similar in appearance although 

females are generally larger and stouter 

than males. Males also have somewhat 

more of a tuft at the abdominal apex.

Eggs are rarely seen. They are oblong 

and slightly fl attened, about 1

/16” long 

and 1

/36” in diameter. The egg surface 

is reddish brown with a fi ne reticulate 

pattern (Figure 3). Larvae are creamy 

white, grayish or pink with red-brown 

heads (Figure 4). Larvae develop 

through four instars that increase in 

size with each molt; the fi nal instar 

reaches an inch or more in length. 

Pupae are about 3⁄4” long, brown with 

prominent spines (Figure 5) extending 

across the top of each abdominal 

segment. 

Life History

The sequoia pitch moth has a 2-year 

life cycle with overlapping generations. 

Figure 2 – Adult male sequoia pitch moth

Figure 3 – Sequoia pitch moth egg.
3

Adults emerge from late May to early 

September, with peak emergence in 

June and July. Adults do not feed and 

only live a few days, during which they 

mate and lay eggs. Males are able to 

locate mates by detecting pheromones 

(sex attractants) emitted by females. 

Females lay their eggs soon after 

mating. Eggs are deposited singly 

in bark crevices or at branch nodes 

of host trees. Females are strongly 

attracted to recent wounds or any 

exudation of pitch from a host tree; 

they preferentially oviposit at those 

locations. Mechanical wounds caused 

by pruning or cone stimulation 

girdling in seed orchards are common 

oviposition sites. In fact, pitch masses 

associated with larval feeding are 

attractive to females, and oviposition 

may occur at these locations repeatedly 

over a period of years.

Eggs hatch in about two weeks. Newlyhatched larvae bore into the cambial 

area of the host tree, where they create 

a shallow cavity and feed on phloem 

until winter temperatures become too 

cold for further activity. They resume 

feeding when temperatures warm. 

Usually two years are required to 

complete the life cycle, so two winters 

are passed in the larval gallery. Larvae 

feed in a winding pattern, causing 

copious amounts of pitch to fl ow at the 

site of entry. These pitch masses can 

become very large; up to several inches 

in diameter, often overlapping (Figure 

6). The larvae are tolerant of pitch, and 

are not drowned or “pitched out” as 

may happen with other phloem-boring 

insects.

Figure 4 – Late instar sequoia pitch moth 

larva.

Figure 5 – Sequoia pitch moth pupa emerging 

from pitch mass. Note spines on the tops of the 

abdominal segments

Figure 6 – Overlapping pitch masses from 

sequoia pitch moth attacks. 
4

feeding by larvae and the associated 

accumulations of pitch attract further 

oviposition and prevent or delay 

healing. Trees with stimulation 

wounds that have not healed are at 

elevated risk of breaking during high 

winds. 

In managed settings, heavy attacks 

over repeated years may result in 

trees that have many overlapping pitch 

masses and abundant pitch fl ows on 

the bole and branches, causing the 

trees to become highly fl ammable. 

In recreational or urban landscape 

settings, abundant pitch fl ows can 

become a serious nuisance (Figure 7). 

Larvae pupate between late April and 

early August, constructing a silk-lined 

chamber at the end of a tunnel in the 

pitch mass close to the surface. The 

pupal stage lasts about 30 days. Just 

before the adult emerges, the pupa 

begins to move toward the surface of 

the pitch mass, aided by rows of spines 

on the dorsal surface of its abdominal 

segments. Eventually the pupa forces 

itself halfway out of the pitch mass, 

and the adult emerges.

Hosts

Principal hosts of sequoia pitch moth 

are lodgepole and ponderosa pine. 

Other known hosts are Monterey pine, 

Bishop pine, Jeffrey pine, piñon pine, 

sugar pine, various ornamental pines, 

and occasionally Douglas-fi r and 

spruce. Host species or cultivars that 

are non-native or off-site, or trees with 

recent bole wounds or pruning wounds 

are most susceptible to attack.

Impacts

In forest settings, sequoia pitch moth 

is a minor, mostly aesthetic pest that 

produces individual cream-pinkish 

pitch masses several inches in diameter 

along tree boles and branches. Mature 

trees can withstand attacks with little 

to no impact on their growth and 

survival. Small trees are more at risk 

of damage. Stems less than four inches 

in diameter can be girdled by larval 

mining. Heavily mined boles and 

branches are susceptible to breakage. 

Sequoia pitch moth can cause 

substantial damage to saplings or seed 

orchard trees. Girdling to stimulate 

cone production in seed orchards 

creates wounds that are attractive 

to ovipositing females. Subsequent 

Figure 7 – Pine with profuse pitching in a 

parking lot in Hood River, Oregon.
5

Evidence of Infestation

Sequoia pitch moth attacks are 

characterized by the development of 

large pitch masses around larval entry 

sites. Current year pitch masses are 

soft to the touch, gradually hardening 

as they get older. The brown shell of 

an empty pupal case often can be seen 

sticking out of a pitch mass from which 

an adult has emerged (Figure 8). 

Pitch tubes from bark beetle attacks 

may be confused with pitch masses 

from sequoia pitch moth. Most bark 

beetle pitch tubes are much smaller, 

generally less than one-half inch in 

diameter. Infestations of pyralid moths 

in the genus Dioryctria are sometimes 

confused with sequoia pitch moth. 

However, Dioryctria infestations 

generally have abundant granular frass 

and relatively little pitch.

Natural Controls

Braconid wasps in the genus Apanteles 

are known to parasitize the larvae of 

some clearwing moths. However, the 

importance of parasites, predators 

and diseases in controlling sequoia 

pitch moth populations has not been 

documented. 

Management

The best way to prevent damage 

from sequoia pitch moth is to avoid 

wounding trees. If pruning is needed, 

it should be done when branches are 

small in diameter to promote rapid 

occlusion of wounds and reduce the 

time these wounds are attractive to 

sequoia pitch moth. The best time of 

year for pruning is generally between 

October and January. Pruning should 

be done before the sequoia pitch moth 

flight period begins in May, and during 

Figure 8 – Empty pupal case from a sequoia pitch moth that has emerged.
6

a season when wounds will exude 

little or no pitch. As wounds heal and 

volatiles in the oleoresin dissipate, 

oviposition sites become less attractive 

to sequoia pitch moths and attacks 

tend to taper off. Avoid planting nonnative pines or planting pine species or 

cultivars that are not suited to the site 

or microclimate.

Individual larvae can be excavated 

from pitch masses and destroyed to 

reduce population numbers. Softer 

pitch masses will contain a single larva 

or pupa, depending on timing, and 

should be removed prior to emergence. 

Over time trees may become less 

attractive to sequoia pitch moth attack. 

Sticky traps baited with 

pheromone lures attractive 

to males are effective for 

identifying when moths are 

fl ying and aid in the proper 

timing of pruning operations. 

“Trapping out” males may 

have limited effectiveness in 

reducing the number of mated 

females in an area. Traps 

and lures are widely available 

from many manufacturers at a 

low price and can be located 

online. 

Individual trees can be 

protected from attack by 

wrapping boles with a fabric, 

which acts as a physical 

barrier to oviposition (Figure 

9). 

No pesticides are currently 

registered for sequoia pitch 

Figure 9 – Fabric tree wrap to prevent sequoia pitch moth moth control.

attacks.
7

Selected Bibliography

Beutenmüller, W. 1901. Memoirs of the 

American museum of natural history 

Vol. 1, Part VI: Monograph of the 

Sesiidae of America, north of Mexico. 

190 p.

Brunner, J. 1914. The sequoia pitch 

moth, a menace to pine in western 

Montana. Bulletin of the USDA No. 

111, 11 p.

Duncan RW. 1996. Common pitch 

moths of pine in British Columbia. 

Canadian Forest Service, Forest Pest 

Leaflet 69.

Furniss RL, Carolin VM. 1977. 

Western forest insects. USDA Forest 

Service, Misc. Publication 1339, p. 

138-140.

Karlik JF, Tjosvold SA, Driestadt DH, 

Perry EJ. 2013. Clearwing moths. 

University of California Cooperative 

Extension Pest Notes, publication 

7477, 6 p. 

Kegley S, Sturdevant N. 2016. Effect 

of trap type on pitch moth trapping 

in western Montana. USDA Forest 

Service, Northern Region, publication 

16-04, 5 p.

Sturdevant N, Kegley S, Crane B, 

Hayes C. 2015. Evaluation of two 

control methods for reducing damage 

from sequoia pitch moth, Big Fork Tree 

improvement Area, Flathead National 

Forest, Montana. USDA Forest 

Service, Northern Region, publication 

15-07, 5 p.

Swain, S.V., Dreistadt, S.H. 2013. 

Pitch moths, integrated pest 

management for home gardeners and 

landscape professionals. University 

of CA Agriculture and Natural 

Resources, publication 7479, http://

ipm.ucanr.edu/PDF/PESTNOTES/

pnsequoiapitchmoth.pdf 4 p.

Wheeler, N.C., Masters, C.J., Cade, 

S.C., Ross, S.D., Keeley, J.W., Hsin, 

L.Y. 1985. Girdling: an effective and 

practical treatment for enhancing seed 

yields in Douglas-fir seed orchards. 

Can. J. For. Res. 15(3): 505-510. 

Acknowledgments

This sequoia pitch moth pest leaflet 

was written by Constance J. Mehmel 

and Christine Buhl. The range map 

was created by Roy Magelssen, 

USDA Forest Service, Wenatchee, 

Washington. Critical reviews were 

provided by Dr. Jay Michael Johnson, 

USDA Forest Service, LaGrande, 

Oregon; Sandra J. Kegley, USDA 

Forest Service, Coeur d’Alene, Idaho; 

and Nancy Sturdevant, USDA Forest 

Service, Missoula, Montana. Photos 

courtesy of USDA Forest Service and 

Oregon Department of Forestry. 
8

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Published by USDA Forest Service, Pacific Northwest Region (R6), Portland, Oregon

FS/R6/RO/FIDL#185-17/001

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