United States 

Department of 

Agriculture 

Forest 

Service 

Northern 

Region 

200 East Broadway 

P.O. Box 7669 

Missoula, MT 59807 

Numbered Report 05-03 May 2005

Cone & Seed Insect Monitoring Report 

North Idaho Seed Orchards 2004

Sandra Kegley, Entomologist 

USDA Forest Service, Northern Region Coeur d’Alene

Introduction 

Insects that feed on cones and seeds are 

common in our forests and can often become 

“pests” in seed orchards where seed is of high 

value from genetically superior trees. This is 

especially true in blister rust resistant western 

white pine (Pinus monticola Dougl.) orchards. 

North Idaho seed orchards are routinely 

examined for cone and seed insects and their 

damage by Tree Improvement and Forest Health 

Protection personnel throughout the spring and 

summer to determine insect abundance and the 

need for treatment. The most important insects 

affecting cones or seed in North Idaho white pine 

seed orchards are cone beetles (Conophthorus 

ponderosae Hopkins), coneworms (Dioryctria 

abietivorella Grote), and seed bugs 

(Leptoglossus occidentalis Heidemann). Cone 

beetles can destroy 90% or more of the western 

white pine cone crop (Shea et al. 1983, 

Williamson et al. 1966). Seed bugs and 

coneworms impacted between 50-80% of cones 

in certain western white pine seed orchards 

(Connelly and Schowalter 1991, Haverty et al. 

1986). Other insects sometimes found on the 

cones or in seed include adelgids (Pineus 

coloradensis (Gillette)), seed chalcids 

(Megastigmus sp.), and the lodgepole cone moth 

(Eucosma rescissoriana Hein.). 

This report documents insects found in 

2004 at western white pine seed orchards at the 

Coeur d’Alene, Lone Mountain, and Grouse 

Creek tree improvement areas. Western larch at 

Grouse Creek is now starting to produce cones 

and was also examined in 2004. 

Methods 

Few practical methods exist for 

monitoring cone & seed insects in western white 

pine. A variety of methods have been tried in the 

past with marginal results including light traps, 

sticky traps, and direct observations using 

ladders and binoculars (Gast 1991). In 2004, 

we examined cones from the height advantage of 

a bucket truck since the majority of cones are 

located in the tops of the trees. Numbers of 

insects or damage seen and cones examined were 

recorded and a percent damage calculated. 

Cones were also examined on the ground as they 

were harvested. 

Attractant pheromones have been 

identified for cone beetles but are not yet 

available for the other insects. Pityol and alphapinene have been shown to be most attractive to 

North Idaho cone beetles (Rappaport et al. 2000). 

Seven Japanese beetle traps fitted with Nalgene 

plastic cups and baited with pityol and alphapinene were placed in the upper crown of trees at 

Grouse Creek white pine seed orchard in early 
2 

April. They were monitored every few days and 

beetles collected. 

Results 

Coeur d’Alene Seed Orchard

This orchard was examined in late May, 

early July, and mid-August. Cone beetle 

damaged cones were obvious and abundant 

during all examinations (Table 1). The decrease 

in cone beetle damaged cones from May and 

July to August is likely not an actual decrease in 

the population but an artificial decrease due to 

attacked cones falling off trees and therefore not 

sampled. Adult seed bugs were found in May 

and both adults and nymphs were abundant by 

early July. Damage by coneworms was just 

starting to be noticeable in early July but became 

quite conspicuous by mid-August. After 

numerous seed bugs were found in July, the 

orchard was sprayed with permenthrin on July 

21, 2004. Seed bugs found in August were 

likely immigrants from surrounding ponderosa 

pine. 

Grouse Creek Seed Orchard 

This orchard was examined in early July 

from a bucket truck, and in mid-August from the 

ground as bushels of cones were collected (Table 

1). Averages of 27% of cones examined in July 

were killed by cone beetles. However, 

individual trees contained higher damage levels. 

Two trees sampled had 71% and 55% of their 

cones killed by cone beetles. Cone beetle 

damage can be fairly spotty with damage in 

certain parts of an orchard or on certain trees. 

No coneworm damage was seen in July and few 

seed bugs noticed. In August, cones were 

examined after they were picked and put into 

bushel baskets. Large numbers of cones can be 

examined this way but cones damaged by cone 

beetles can be missed either because they fell off 

the tree already or because they were very small 

and not picked. Only 15% of cones examined 

from bushels showed evidence of cone beetles, 

while 26% had evidence of coneworm feeding 

(mainly frass). 

Cone beetles were caught in pheromone traps 

from April 12-June 29 (fig. 1). Traps were 

monitored every few days and trap catch 

numbers pooled each week. Peaks in beetle 

flight occurred in the 2nd week of April and 1st

and 3rd weeks of May. The drop in trap catch 

numbers the 3rd week of April was likely due to 

cool, wet weather. Flight was over by the end 

of June. 

Table 1. Numbers of cones examined and insect damage recorded by seed orchard. 

Orchard Date 

examined 

# 

cones 

# trees Clean* 

cones 

Cone 

beetles 

Coneworms Adelgids Seedbug 

adults 

Seedbug 

nymphs 

5-24-04 264 13 54% 44% 0 0 5 0 

7-6-04 532 20 56% 43% 0.2% 1% 12 14 

Coeur 

d’Alene 

8-12-04 210 10 42% 26% 32% 0 2 6 

Lone 

Mtn. 

7-19-04 356 15 98% 1.4% 0.6% 0 1 0 

Grouse 7-8-04 268 12 73% 27%** 0 0 3 0 

Creek 8-17-04 897 bushels 

examined 

59% 15% 26% 0 3 0 

*clean cones = cones with no external damage 

**two sampled trees had 71% and 55% of their cones killed by cone beetles 
3 

Cone Beetle Trap Catches

Grouse Creek Seed Orchard 2004

0

5

10

15

20

25

30

35

40

2nd-Apr

3rd-Apr

4th-Apr

1st-May

2nd-May

3rd-May

4th-May

1st-June

2nd-June

3rd-June

4th-June5th-June

1st-July

Week/Month

Traps placed April 7

Fig. 1. Cone beetle trap catches at Grouse Creek seed orchard in 2004.

Developing cones from the larch seed 

orchard were also examined in early July. At 

that time, we discovered many cones that were 

slightly stunted but had no other signs of insect 

damage. These cones were brought to the lab 

and later produced frass and caterpillars of 

Dioryctria sp. (coneworms). 

Lone Mountain Seed Orchard

This orchard was examined only once, in 

mid-July. Cones were examined from Phase II 

and mid-elevation sections. Very little 

coneworm and cone beetle damage was found 

and few seed bugs were noticed (Table 1). 

Insect Biology 

Cone beetles

The ponderosa pine cone beetle, C. 

ponderosae Hopkins (=contortae Hopkins, = 

monticolae Hopkins, =flexilis) is the only cone 

beetle species affecting pines in the Inland 

Northwest (Wood 1982). It infests western 

white pine, ponderosa pine (P. ponderosa), 

lodgepole pine (P. contorta) (Furniss 1997), and 

even high elevation limber pine (P.flexilis)(Keen 

1958) and whitebark pine (P. albicaulis)(Kegley 

et al. 2001). Cone beetles are in the same family 

as bark beetles (Scolytidae) and are small, dark 

brown beetles, about 1/8 – 3/16 inches long. 

Cone beetles spend the winter inside cones killed 

the previous summer, and begin to fly in April or 

May as soon as ambient temperatures are 

consistently in the 60’s. They attack developing 

second year cones, often leaving a characteristic 

pitch tube at the base of the cone (fig. 2). 

Developing cones are killed rapidly by the adult 

beetles girdling the cone axis causing them to be 

stunted. Eggs are laid and larvae hatch and feed 

inside the cone. Feeding of larvae pulverize the 

inside of cones into a powder. Larvae develop 

into immature adults by the fall to overwinter 

again in cones. White pine cones killed by cone 

beetles usually fall to the ground and in winter 

are covered by snow, offering protection from 

extreme weather conditions for overwintering 

beetles (Williamson et al. 1966). 
4 

Fig.2. Pitch tube on outside of cone attacked by 

cone bettle. 

Seed Bugs 

Western conifer seed bugs have been 

observed feeding on Douglas-fir and several 

species of pine from British Columbia to Mexico 

(Koerber 1962). Adult seed bugs hibernate over 

the winter—often invading people’s houses in 

the fall—and emerge in spring. They are strong 

fliers and are easily disturbed. Mating and egg 

laying occur in late May through early July. 

Eggs are laid in rows on needles. Seed bug 

nymphs look similar to adults only smaller and 

with more orange on their abdomens (fig. 3). 

They are gregarious, do not have wings, and do 

not fly. Both nymphs and adults feed on seed 

from the outside of cones. They have a long, 

sucking beak (mouthpart) that they insert 

through cone scales to a seed. Seed contents are 

dissolved by seed bug saliva and then consumed. 

Seed bug feeding causes the endosperm of the 

seed to shrivel. Damaged seeds are not viable 

and can be detected by radiography or 

biochemical marker based techniques (Lait et al. 

2000, Bates et al. 2002). Seed bug feeding early 

in the growing season can also cause substantial 

abortion of developing 2nd year white pine cones 

(Connelly and Schowalter 1991). 

Coneworms 

The fir coneworm, D. abietivorella, has a 

broad host range. It has been found infesting true 

firs, Douglas-fir, many species of pine, spruces, 

western larch, and western hemlock in Canada, 

the northeastern United States, and in the west 

from Alaska to northern Mexico (Sopow et al. 

1996). Its life cycle is not well known. 

Pheromone trap testing in high elevation 

whitebark stands caught a few moths in July and 

August (Kegley et al. 2001). At Grouse Creek 

seed orchard in 2002, a few moths were trapped 

data). With so few moths caught, we are unsure 

when their peak flight occurs in north Idaho, but 

we do know that they are present during the 

summer months as early as late June. In a study 

of infested cones that were bagged on the trees in 

August to prevent insect escape, 37% of 

coneworms emerged from cones and spun silk 

hibernacula inside of the bags to overwinter. 

Another 42% of the larvae spun a silk chamber 

on or inside the cone. Of the remaining larvae, 

13% developed into adults before winter and 8% 

were parasitized by wasps (Gast 1991). This 

indicates that the majority of the population 

spends the winter either as pupae or pre-pupae in 

cones or in the duff and emerges as adults in the 

summer. A small portion of the population 

develops into adults in late summer. Whether 

they spend the winter as adults or lay eggs before 

winter is unknown. Larvae are purplish-brown 

in color, are very mobile and will emerge from 

one cone to feed on another. Their feeding may 

cause discoloration on the outside of the cone 

with conspicuous frass in mid- to late-summer 

(fig. 4). 

Fig. 3. Seedbug nymphs on western white 

pine cone. 
5 

Insect Management 

The most effective method of controlling 

insects in seed orchards is using an integrated 

pest management system including monitoring, 

sanitation, pheromones (when available), and 

correct timing of treatments. 

Since many insects spend the winter 

inside damaged cones, removing these cones 

each year will remove resident populations and 

should be done annually. However, immigration 

of insects from surrounding forests can also be a 

problem. 

Single or multiple applications of 

synthetic pyrethroids have been effective in 

reducing cone crop damage due to the 

aforementioned insects. However, multiple 

applications of these insecticides within a 

summer have sometimes led to outbreaks of 

scale insects. Timing of insecticide applications 

is critical since many of the insects are protected 

once they bore into the cones. Timing must 

coincide with adult activity outside the cone 

which varies by insect species. Seed bugs are 

active from May through September. Cone 

beetles fly in spring—usually April and May. 

Coneworm life cycle is not well known but two 

applications of fenvalerate, once in May and 

once in June significantly increased seed yield 

and protected cones from coneworms (Haverty et 

al. 1986). Applications of behavioral chemicals 

such as 4-allylanisole (4aa) against cone beetles, 

have been used elsewhere with promising 

results. These may be available in the future as 

formulations improve (Nancy Gillete, personal 

communication). 

Pheromones in traps can be used to 

monitor insect populations and help in timing of 

insecticide treatments. However, at this time, 

only cone beetle pheromones are currently 

available. Using pheromones to “trap out” cone 

beetles have been tried in the past. But current 

pheromones trap mostly males, and even 

unmated females continue to kill cones. In 

addition, trap-outs over several years have not 

shown a reduction in cone damage (Nancy 

Gillete, personal communication). Research 

continues to try to identify pheromones attractive 

to female beetles. We have tested different 

pheromones for many years in an attempt to 

attract coneworm adults. The pheromones 

identified appear to be unstable and none have 

consistently caught a sufficient number of moths 

in the field. More recently, research had 

identified a new pheromone which has shown 

promise in the field and may be available for use 

in the near future (Nancy Gillete, personal 

communication) 

Prescribed burning in seed production 

areas in the Midwest have been successful in 

reducing damage from the red pine cone beetle, 

Conophthorus resinosae Hopkins, red pine cone 

moth, Eucosma monitorana Heinrich and the red 

pine coneworm, Dioryctria disclusa Heinrich 

(Miller 1978). Use of a propane flamer for 

control of white pine cone beetles, Conophthorus 

coniperda (Schwarz) has also been used with 

success in the Midwest (Sery and Katovich 

1996). This technology has potential to be 

useful in western white pine orchards. 

Fig. 4. Western white pine cone damaged by 

coneworms (left) compared to normal cone 

(right). 
6 

Acknowledgements 

Many thanks to Dave Foushee and Kevin Naffin 

who consistently provide support for monitoring 

and pheromone testing. Thanks also to Tom 

Flynn, and Kester Poole who help run the bucket 

trucks and check traps. 

References 

Bates, S.L.; Lait, C.G; Borden, J.H.; and 

Kermode, A.R. 2002. Measuring the 

impact of Leptoglossus occidentalis

(Heteroptera: Coreidae) on seed 

production in lodgepole pine using an 

antibody-based assay. Journal of 

Economic Entomol. 95(4): 770-777. 

Connelly, A.E.; Schowalter, T.D. 1991. Seed 

losses to feeding by Leptoglossus 

occidentalis (Heteroptera: Coreidae) 

during two periods of second-year cone 

development in western white pine. J. 

Econ. Entomol. 84(1): 215-217. 

Gast, S. 1991. Cone and seed insect surveys in 

north Idaho western white pine seed 

orchards 1991. USDA For. Serv. 

Northern Region FHP Rpt. 4 p. 

Haverty, M.I.; Shea, P.J.; Stipe, L.E. 1986. 

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(Lepidoptera: Pyralidae). J. Econ. 

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Keen, F.P. 1983. Cone and Seed Insects of 

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pine. USDA For. Serv. Northern Region 

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7 

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Personal Communication

Nancy Gillette, Research Entomologist, USDA 

Forest Service, PSW Research Station, 

Albany, California.