Common Vegetable Insects that can be monitored using degree days or indicator plants
Cabbage Maggot Degree Days
Base temperature = 43°F
- 300; 1,476; 2,652 DD43 for 1st; 2nd; & 3rd generations flies
- 1st generation eggs are laid when the common lilac is in full bloom
Colorado Potato Beetle (First gen), Degree Days
Base temperature = 50°F
- Begin counting when first eggs appear
- 1st instar larva at 185 DD50
- 2nd instar larva at 240 DD50
- 3rd instar larva at 300 DD50
- 4th instar larva at 400 DD50
- Pupa at 675 DD50
Common Asparagus Beetle Degree Days
Base temperature = 50°F
- Egg laying at 150 – 240 DD50
(Amelanchier full bloom, redbud early to full bloom, Black Hills spruce bud caps splitting)
Corn Rootworm Degree Days
Base temperature = 50°F
- Adult beetles present at 1,300 DD50
(Canada thistle seed ripe, Queen Anne’s lace early bloom)
European Corn Borer Degree Days
Base temperature = 50°F
- 1st spring moths at 375 DD50
(Spiraea x vanhouttei in full bloom) - 1st eggs at 450 DD50
(Pagoda dogwood late bloom) - Peak spring moths at 631 DD50
(Black locust full bloom) - 1st summer moths at 1,400 DD50
(Mountain-ash fruit golden yellow, most Canada thistle seed ripe) - 1st eggs at 1,450 DD50
- 1st egg hatch at 1,550 DD50
- Peak summer moths at 1,733 DD50
- Summer treatment period at 1,550 – 2,100 DD50
(Queen Anne’s lace full bloom – 1,500 to goldenrod early bloom – 2,100)
Fleabeetle Degree Days
Base temperature = 50°F
- 150-200 DD50
(Norway maple late bloom, Amelanchier blooming, redbud early bloom)
Imported Cabbageworm Degree Days
Base temperature = 50°F
- Adult butterflies at 150-240 DD50
(Amelanchier full bloom, redbud early to full bloom, Black Hills spruce bud caps splitting)
Onion Maggots
Base temperature = 40°F
- 680, 1950, 3230 DD40 for 1st, 2nd, & 3rd generation flies
- 1st generation eggs laid 230-280 DD40
Squash Vine Borer Degree Days
Base temperature = 50°F
- Egg laying at 900-1,000 DD50
(Chicory full bloom)
Seed Corn Maggot Degree Days
Base temperature = 39°F
- 200, 600 for 1st and 2nd generation flies
Common Fruit Insects that can be monitored by degree days or indicator plants
Apple Maggot* Degree Days
Base temperature = 50°F
- 1st adult fly emergence 900 DD50
- 1st egg laying 1,100 DD50
- Peak fly emergence 1,600 DD50
- Peak egg laying 1,750 DD50
- End of fly emergence 2,800 DD50
*These degree days assume normal soil moisture. Under dry conditions, all apple maggot events will be delayed until the soil is moist.
Codling Moth Degree Days
Base temperature = 50°F
- 1st generation moth emergence 150 DD50
- Eggs laid 250 DD50
- 1st generation peak moth emergence 500 DD50
- Peak egg laying 550 DD50
- 2nd generation first moth emergence 1,150 DD50
- 2nd generation peak moth emergence 1,600 DD50
- 2nd generation peak egg laying 1,700 DD50
Obliquebanded Leafroller Degree Days
Base temperature = 43°F
- 1st generation moth emergence 600 DD43
- 1st generation peak moth emergence 800 DD43
- 1st generation peak egg laying 1,250 DD43
- 2nd generation moth emergence 2,050 DD43
- 2nd generation first eggs laid 2,300 DD43
Author: Karen Delahaut, UW-Madison Fresh Market Vegetable Program
Revised: 8/6/2012
Item number: XHT1087
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