Swede Midge Introduction, Damage and Biology Cornell Cooperative Extension Christy Hoepting Cornell...

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