swede midge introduction, damage and biology cornell cooperative extension christy hoepting cornell...
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Swede Midge Introduction, Swede Midge Introduction, Damage and BiologyDamage and Biology
Cornell Cooperative Extension
Christy Hoepting
Cornell Cooperative Extension
Vegetable Program
Swede Midge• Serious insect pest of cruciferous plants:
– vegetables (i.e. broccoli, cauliflower, Brussels sprouts, cabbage, collards, swede/turnip, Asian vegetables (i.e. bok choy, etc.)
– canola– weeds (i.e. shepherd’s purse, wild mustard)– Ornamental crucifers
• Common and endemic in Europe:– Known since late 1800s– Major pest in Belgium, Germany, Switzerland,
Netherlands, France, Poland and Slovania
Swede Midge in North America
• 2000: first identification in Ontario, Canada (Hallett & Heal)– Symptoms observed at least since 1996, but
erroneously attributed to a molybdenum deficiency
• Economic losses occur in Canada and in parts of New York State:– up to 85% losses– Especially in organic and small-scale operations
Swede Midge: Adult
Adult female Adult male
Length: 0.3 mmWidth: 0.08 mm
Swede midge: eggs
Deep in the youngest actively growing vegetative tissue
Swede midge: larvae
0.3 to 3-4 mm
Damage: Blind head, brown scarring at growing point
broccoli
Damage: Leaf puckering
Green cabbage
Damage: Leaf puckering
broccoli
Damage: Leaf puckering
Red cabbage
Damage: Leaf puckering
cauliflower
Damage: Multiple shoots, growing points
broccoli
Damage: Multiple small heads
Red cabbage
Damage: Brown corky scarring in head
cauliflower
Damage: Brown corky scarring in head
broccoli
Damage: Brown corky scarring in head
Green cabbage
Damage: Secondary soft rot
Swede midge larvae in an infested growing tip
Damage: Swollen Flower Buds
Damage: Swollen Florets
broccoli
Swede midge damage in canola
Field pennycress
Swede midge damage on weeds
Swede Midge Damage Severity
Increases…• as number of larvae per
plant increases• the earlier in
development that the plant is infested
• later in the season as the population builds
• in sheltered areas near hedgerows, buildings, treelines
Crucifers are susceptible to swede midge all season long
Swede Midge Life CycleEggs ~0.3 mm
Transparent to creamy white
2-50 eggs/cluster100 eggs /female
Larvae ~0.3 to 3-4 mmTransparent on first hatch to yellow
when mature, feed gregariously at plant growing tip
Pupae ~2-4 mmmost within top 2 cm of soil,
Optimum 25-75% soil moisture for emergence
Pre-pupae
Adults ~1.5 to 2 mm 4-5 over-lapping generations
Overwintering Cocoons
Survive in soil > 1 year
Mating1-5 days
Soil
3 days
drou
ght
moi
stu
re
May-JuneJuly
July-AugustAugust
Sept - Oct
Emergemid-May
7-21 days7-14 days
21-44 daysper generation
0
50
100
150
200
250
300
350
400
450
Jun
2-Ju
n 5
Jun
5 - J
un 8
Jun
8-Ju
n 13
Jun1
3-Ju
n16
Jun
16-J
un 2
0
Jun
20-J
un 2
3
Jun
23-J
un 2
7
Jun
27- J
un 3
0
Jun
30-J
ul 4
Jul 4
- Ju
l 7
Jul 7
-Jul
10
Jul 1
0-Ju
l 14
Jul 1
4-Ju
l 18
Jul 1
8 - J
ul 21
Jul 2
1-Ju
l 25
Jul 2
5 - J
ul 28
Jul 2
8 - J
ul 31
Jul 3
1 - A
ug 4
Aug 4
- Aug
8
Aug 8
- Aug
11
Aug 1
1 - A
ug 1
5
Aug 1
5 - A
ug 1
8
Aug 1
8 - A
ug 2
2
Aug 2
2 - A
ug 2
5
Aug 2
5 - A
ug 3
0
Aug 3
0 - S
ept 5
To
tal
# S
M C
aptu
red
on
3 T
rap
s
Wellington CtyHamilton/Wentworth CtySimcoe Cty
J. Allen, M. Paibomesai and H. Fraser, 2006
2006 Swede Midge Trap Activity – Ontario, Canada