swede midge |
Insects: Gallmaker Insects |
|
Hexapoda (including Insecta) > Diptera > Cecidomyiidae > Contarinia nasturtii (Kieffer)
|
| Synonym(s): cabbage crowngall fly, cabbage gall midge |
| Swede midge is native to Europe and southwestern Asia. It was confirmed
to be present in Ontario and Québec, Canada and has been detected in
New York. Since the adults are weak fliers, it was most likely introduced
through the movement of infested plants or soil. Hosts of this pest are
plants in the family Brassicaceae: and includes plants such as broccoli,
cauliflower, collard, kale, cabbage, and radish. The number of generations
per year is dependent on the climate, with as many as 4 generations per
year in parts of Europe and 3 per year in Ontario. Adults of the
overwintering generation begin to emerge at the end of May. The female
lays eggs in strings or clusters of 15-20 eggs on the youngest parts of the
plant. The extremely small eggs are laid on a stalk. After three days, the
eggs hatch and most larvae will start to feed near the growing point. The
larvae are pale to lemon-yellow and legless. When full grown, they can be
up to 1/16 of an inch in length. Their saliva digests plant tissue, resulting
in the flower (i.e. head of broccoli or the like) becoming deformed and
unmarketable. The damage by the insect also favors the development of
plant-rotting fungi and bacteria. After 2-3 weeks the larvae drop to the
ground and spin cocoons. Two weeks later the next generation of flies
appear. Adults are 1/16 of an inch in length with iridescent wings. The
abdomen has indistinct transverse stripes. The ovipositor of females is
whitish and can extend to become pointed like a needle. The shield
behind the head is slate gray with two lengthwise, shiny-black furrows.
Females become inactive at temperatures below 68 °F (20 °C). During
periods of drought, the larvae may become dormant, but growth resumes
after a rainfall. Feeding damage is easily confused with mechanical injury
from cultivation, feeding by other insects and animals, molybdenum
deficiency, herbicide injury, genetic variation of the plant, and heat or cold stress. |
| Image |
Descriptor |
Description |
Photographer |
| 1253039 |
Adult(s) |
Female |
Susan Ellis |
| 1253040 |
Adult(s) |
Female |
Susan Ellis |
| 1253041 |
Adult(s) |
Female |
Susan Ellis |
| 1253046 |
Adult(s) |
Male |
Susan Ellis |
| 1253047 |
Adult(s) |
Male |
Susan Ellis |
| 1253050 |
Adult(s) |
Male |
Susan Ellis |
| 2134066 |
Damage |
Damaged red cabbage. Note twisted leaves, swelling |
Julie Kikkert |
| 2134067 |
Damage |
Damaged red cabbage followed by bacterial soft rot and collapse of plant |
Julie Kikkert |
| 2134068 |
Damage |
Swede midge damaged plant. Note brown scarring, multiple stems, twisted leaves. |
Julie Kikkert |
| 2134069 |
Damage |
Damaged red cabbage |
Julie Kikkert |
| 2134070 |
Damage |
Damaged green cabbage |
Julie Kikkert |
| 2134071 |
Damage |
Damaged plant - leaf twisting, brown scarring |
Julie Kikkert |
| 2134072 |
Damage |
Damaged transplant - swollen petiole, brown scars |
Julie Kikkert |
| 2134073 |
Damage |
Damaged green cabbage - twisted leaves, rotten center |
Julie Kikkert |
| 1253048 |
Feature(s) |
Male genitalia |
Susan Ellis |
| 1253049 |
Feature(s) |
Male genitalia |
Susan Ellis |
| 1253042 |
Feature(s) |
Labeled Male Head |
Susan Ellis |
| 1253043 |
Feature(s) |
Spatula |
Susan Ellis |
| 1253051 |
Feature(s) |
Head |
Susan Ellis |
| 1253057 |
Feature(s) |
Spatula |
Susan Ellis |
| 1253045 |
Feature(s) |
legs |
Susan Ellis |
| 2134065 |
Larva(e) |
Swede midge larvae and feeding damage on cauliflower. Swede midge larvae prefer to feed on growing tips but in high densities they occupy the stem and the leaves. |
Mao Chen |
| 1253044 |
Larva(e) |
|
Susan Ellis |
| 2134064 |
Pupa(e) |
body size 1.3 mm |
Mao Chen |
|
