One of the most destructive early season pests of crucifers and certain root crops in NH. It can cause severe injury to cabbage, cauliflower, broccoli, Brussels sprouts, radish, turnip, rutabaga, beets and celery if not controlled.
The adult fly is similar in appearance to the common house fly, but smaller (1/4-inch long). It is dark, ashy gray with black stripes on the thorax and black bristles over the body. In the spring, female flies are commonly seen flying close to the ground, depositing small white eggs in cracks and crevices near the stems of host plants.
Larvae destroy plant roots by their tunneling habit. This will often cause young cabbage, broccoli and cauliflower seedlings to wilt and die. Plants like radish and turnip become scored with feeding trails, making them susceptible to attack by disease organisms.
There are typically 3 or 4 generations of CM each growing season in New Hampshire.
Prevention and non-chemical control
Cover cabbage family transplants or newly-seeded rows with floating row covers until June 1, or delay planting until then to foil the first generation of egg-laying cabbage maggot flies. Alternatively, protect cabbage, broccoli, cauliflower and other cole crop transplants with barriers made by punching a hole in the center of a six-inch square of tarpaper and slitting the paper from one corner to the center hole. Then place the tarpaper square flat on the ground, with center hole snugly encircling the stem of the transplant.
Bottom Line for Pest Control….
OBSERVE! Use floating row covers to minimize heavy infestations. Squish or dispose of pests in container of soapy water. Dispose of garden debris. Mow your borders and dispose of standing weeds. If your soil is strong, your plants will be strong and able to withstand some assaults—the plants may be a little ragged for a bit but they can recover! And remember—this is supposed to be FUN!
Feel free to continue the conversation and add your own discoveries on pest control by leaving a comment. If you have had great success with a particular organic method, let us know what worked for you! Thanks!
ACKNOWLEDGMENTS: The information above was gleaned from the UNH Cooperative Extension Website a GREAT resource!