GDD of Conifer Insects

The table below shows the growing degree days (GDD) for forecasting conifer insect life stages. Read about using growing degree days for integrated pest management.

GDD for forecasting conifer insect life stages

Insect

Life stage

GDD50

Relevant degree day maps

Reference

Arborvitae leafminer

larvae in mines; 1st generation

245-360

250, 300, 350

1

Arborvitae leafminer

2nd generation

533-700

500, 600, 700

1

Arborvitae leafminer

3rd generation

1700-2100

1700, 1900, 2000

1

Balsam gall midge

adults laying eggs

150-300

150, 200, 300

3

Balsam gall midge

galls apparent

550-700

550, 650, 700

3

Balsam twig aphid

egg hatch

60-100

50, 100

4

Balsam twig aphid

stem mothers present (control target)

100-150

100, 150

4

Black pineleaf scale

egg hatch

1068

1050

1

Cooley spruce gall adelgid

1st adults active - Spruce (control target)

25-120

50, 100

3

Cooley spruce gall adelgid

1st galls visible - Spruce

200-310

200, 250, 300

3

Cooley spruce gall adelgid

1st adults active - Douglas fir

90-180

100, 150

1

Cooley spruce gall adelgid

1st nymphs - Douglas fir (control target)

90-150

100, 150

3

Cooley spruce gall adelgid

2nd nymphs - Douglas fir (control target)

600-1000

600, 800, 1000

3

Cooley spruce gall adelgid

2nd adults active (control target)

1500-1600

1500, 1550, 1600

3

Eastern pine shoot borer

1st adults active

75-200

50, 100, 200

3

Eastern spruce gall adelgid

1st adults active (control target)

25-100

50, 100

3

Eastern spruce gall adelgid

egg hatch, galls begin forming

250-310

250, 300

1,3

Eastern spruce gall adelgid

2nd adults active (control target)

1500-1600

1500, 1550, 1600

3

Euonymus scale

egg hatch - 2nd generation

1900-1050

*

1

European pine sawfly

1st larvae

100-195

100, 150, 200

1,3

European pine shoot moth

1st larvae

50-220

50, 100, 200

3

European pine shoot moth

egg hatch

900-1000

900, 950, 1000

3

European pine shoot moth

adults active

700-800

700, 750, 800

3

Gypsy moth

egg hatch, 1st larvae

145-200

150, 200

1, 3

Gypsy moth

young caterpillars

450

450

1

Gypsy moth

pupation

900-1200

900, 1000, 1200

3

Introduced pine sawfly

1st larvae

400-600

400, 500, 600

3

Jack pine budworm

young larvae feeding

300-350

300, 350

3

Jack pine budworm

large larvae feeding - defoliation apparent

650-700

650, 700

3

Jack pine sawfly

eggs; young larvae

100-200

100, 150, 200

1

Jack pine sawfly

larger larvae consuming needles

275-500

250, 350, 500

1

Juniper scale

egg hatch

550-700

550, 600, 700

1

Larch casebearer

egg hatch

120-150

100, 150

1

Northern pine weevil

1st adults active

25-100

50, 100

3

Northern pine weevil

2nd adults active

1200-1400

1200, 1300, 1400

3

Pales weevil

1st adults active

25-100

50, 100

3

Pales weevil

2nd adults active

1200-1400

1200, 1300, 1400

3

Pine chafer (Anomela beetle)

1st adults active

450-600

450, 500, 600

3

Pine engraver (Ips bark beetle)

1st adults active

100-150

100, 150

100, 150

Pine needle midge

1st adults active

400-500

400, 450, 500

3

Pine needle scale

1st generation egg hatch

250-400

250, 300, 400

1,3,5,7

Pine needle scale

1st generation - hyaline stage (control target)

400-500

400, 500

5

Pine needle scale

2nd generation egg hatch

1250-1350

1250, 1300, 1350

1,3,5

Pine needle scale

2nd generation - hyaline stage (control target)

1500

1500

5

Pine root collar weevil

1st adults active

300-350

300, 350

3

Pine root collar weevil

2nd adults active

1200-1400

1200, 1300, 1400

3

Pine shoot beetle

new adults emerge; begin shoot-feeding

500-550

500, 550

6

Pine shoot beetle

optimal control window

450-500

450, 500

6

Pine tortoise scale

egg hatch begins; 1st crawlers

400-500

400, 450, 500

3

Pine tortoise scale

egg hatch ends; last of the crawlers

1000-1200

1000, 1100, 1200

3

Pine tube moth

adults; egg laying; caterpillars

90-250

100, 200, 250

1

Red-headed pine sawfly

1st larvae

400-600

400, 500, 600

3

Spruce budscale

egg hatch, 1st crawlers

700-1150

700, 900, 1150

1,3

Spruce budworm

1st larvae

200-300

200, 250, 300

3

Spruce needleminer

1st larvae

150-200

150, 200

3

Spruce spider mite

1st egg hatch

150-175

150, 200

1,3

Striped pine scale

egg hatch

750-800

750, 800

1

Turpentine beetle

parent beetles colonizing brood material

300-350

300, 350

3

White pine weevil

1st adults active

25-220

50, 100, 200

3

White pine weevil

2nd adults active

1200-1400

1200, 1300, 1400

3

Zimmerman pine moth

1st larvae

25-100

50, 100

7

Zimmerman pine moth

adult flight

1700

1700

1

References
1 = Herms,D.A. Using degree days and plant phenology to predict pest activity. Chapter 11. Tactics and Tools for IPM.
2 = Sadof, C.S. 1994. Recommendations for managing insects and mites on shade trees and shrubs. Purdue University, Dept. of Entomology publication E-41. West Lafayette, IN. 117 p.
3 = MSU observations
4 = Fondren, K. and D.G. McCullough. 2002. Biology and management of balsam twig aphid. MSU Extension bulletin E-2813. 4 p.
5 = Fondren, K. and D.G. McCullough. 2002. Biology and management of pine needle scale. MSU Extension bulletin E-2812. 4 p.
6 = McCullough, D.G. and C.S. Sadof. 1998. Evaluation of an integrated management and compliance program for Tomicus piniperda (Coleoptera: Scolytidae) in pine Christmas tree fields. Forum Article, Journal of Economic Entomology 91:785-795.
7 = Eliason, E.A. and D.G. McCullough. 1997. Survival and fecundity of three insects reared on four varieties of Scotch pine Christmas trees. Journal of Economic Entomology 90:1598-1608.

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