Swede Midge Damage and Biology

Cornell Cooperative Extension

Swede Midge Introduction, Damage and Biology 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

Swede midge: eggs

Length: 0.3 mm Width: 0.08 mm

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

Swede midge damage on weeds Field pennycress

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 Cycle 3 days

drought

Transparent to creamy white 2-50 eggs/cluster 100 eggs /female

Mating 1-5 days

Soil moisture

Eggs ~0.3 mm

Adults ~1.5 to 2 mm 4-5 over-lapping generations

Larvae ~0.3 to 3-4 mm 21-44 days per generation

Emerge

Transparent on first hatch to yellow when mature, feed gregariously at plant growing tip

mid-May

7-21 days

7-14 days Pupae ~2-4 mm Overwintering Cocoons

May-June July July-August August Sept - Oct

Survive in soil > 1 year

Pre-pupae

most within top 2 cm of soil, Optimum 25-75% soil moisture for emergence

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Total # SM Captured on 3 Traps

2006 Swede Midge Trap Activity – Ontario, Canada 450

400

Wellington Cty Hamilton/Wentworth Cty Simcoe Cty

350

300

250

200

150

100

50

0

J. Allen, M. Paibomesai and H. Fraser, 2006