IPM Methods:  Pest Monitoring Timeline

Timeline of insect degree days/calendar date/plant phenology for key life stages of orchard insects.  Dates are estimated for northern Utah, western Colorado, and Idaho; and degree days are provided for a lower temperature threshold of 50, unless otherwise noted.

Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
Box Elder Bug adult adults find hosts April
adult 2nd gen. nymphs full grown Aug - Sept
adult most migration before overwintering Oct
Campylomma Bug eggs egg hatch 1st pink of apple
nymphs time to monitor 1st gen. mid-April - early June
nymphs summer gen. nymphs active June - Sept
adults adults active late-may - late Sept
Codling Moth pre-emergence hang trap 100 - 150
adult moth emergence begins; get biofix 175 - 290
    degree days post biofix:
larvae egg hatch begins 220 - 250
adult 1st flight peak 325 - 581
larvae period of greatest egg hatch 340 - 640
larvae egg hatch ends 1st gen. 920
eggs egg laying begins 2nd gen. 1000 - 1050
larvae egg hatch begins 2nd gen. 1100
larvae max hatch period 2nd gen. 1320 - 1720
adult 2nd flight peak 1337 - 1977
larvae egg hatch ends 2nd gen. 2100
larvae egg hatch begins 3rd gen. 2160
Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
European Red Mite (base 51) eggs 1st egg hatch 100 - 168
nymphs summer egg hatch 424 - 572
Flatheaded Appletree Borer adult adult flight period June - Aug
Greater Peachtree Borer pre-emergence hang trap 400
adult moth emergence begins 575 - 650
adult moth flight period mid June - Oct
Green Apple Aphid eggs egg hatch ¼” green
nymphs start scouting petal-fall - hardened terminals
nymphs population builds up late May - early June
Green Fruitworm adult moth emergence begins early spring
larvae hatching spring
Green Peach Aphid
(base 39)
nymphs eggs hatch pink - full bloom
Leaf Blister Mites adults adults move to new leaf growth early spring
adults adults enter bud scales to overwinter Aug - Sept
Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
Lygus Bug
(base 54)
eggs egg laying 252 - 300
nymphs egg hatch 371
adult summer gen. adults begin 623
Obliquebanded  Leafroller
(base 43)
pre-emergence hang trap; get biofix May
larvae peak egg hatch 600 - 1000
adult 2nd gen. moth emergence begins 1480 - 1683
adult 2nd gen. flight peak 1784 - 2108
Peach Twig Borer pre-emergence hang trap 300 - 330
adult moth emergence begins; get biofix 400 - 450
    degree days post biofix:
larvae 5-28% egg hatch; best time to treat 300 - 400
adult 2nd gen. moth flight begins 900 - 1080
larvae 2nd gen. egg hatch; time to treat 1200 - 1360
adult 3rd gen. flight begins 1760
larvae 3rd gen. egg hatch; time to treat 2140 - 2340
Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
Pear Psylla adult adults active 0 - 49
egg 1st gen. egg laying 1 - 72
larvae 1st gen. egg hatch 60 - 166
adult 1st hardshell stage observed 312
larvae 2nd gen. egg hatch 584 - 750
Pear Sawfly eggs look in terminals April
adults/eggs adults emerge/ lay eggs early June
larvae larvae feed June
adults 2nd gen. adults emerge late July - Aug
Prionus Root  Borer adults adult emergence July
adults active in summer months summer
Root Weevil
(base 40)
pupae pupal development begins 564
adult adult emergence begins 1056
eggs 1st egg laying 1498
adult first leaf feeding observed; apply treatment early summer
larvae treat overwintering larvae late summer - early fall
Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
Rosy Apple Aphid nymphs overwintering eggs start hatching 56
adults wingless adults active early bloom - late June
adults migrate to weed hosts late June - early July
eggs adult female lays eggs for overwintering late summer - early fall
Rust Mite adults adults active (decline in hot weather) 1st bloom - early fall
San Jose Scale pre-emergence hang trap 120 - 150
adult adult male emergence begins; get biofix 177 - 322
    degree days post biofix:
crawlers crawlers begin hatching 300 - 413
crawlers treat crawlers 600 - 700
adult 2nd gen. flight peak 1426 - 1776
crawlers 2nd gen. crawlers emerge 1916 - 2104
Spider Mite (McDaniel’s, Two-spotted) adult rapid reproduction in high heat mid to late summer
Stink Bugs adult adult emergence period May - June
Insect or Mite Life stage Event/Activity Degree Days, Date, or Phenology Range
Walnut Husk Fly
(base 41)
adult adult emergence begins 1890
eggs egg-laying begins 2480
larvae egg hatch begins 2700
Western Cherry Fruit Fly
(base 41)
pre-emergence hang trap 750 - 800
adult adult emergence begins; watch trap 900 - 950
adult treat when fruit develops first salmon blush fruit color salmon blush
adult 3% of flies emerged 1060
adult last adult catch 3049
Western Tentiform Leafminer adult adult emergence begins early spring
eggs egg-laying begins pink
eggs egg-laying peaks bloom
larvae first mines observed early - mid May
adult 1st summer gen., followed by 2 more overlapping generations early June - late summer
White Apple Leafhopper nymphs egg hatch first pink
adult 2nd gen. egg hatch late July - early Aug
Woolly Apple Aphid nymphs & adults first observation above ground June - July
nymphs & adults first treatment if population was high last year early - mid Jul