Small white worm maggots feeding on your cabbage family plants? Could be hylemya brassicae, the cabbage maggot. Find out more.
What is it?
There are many plants in the cabbage family, they include broccoli, brussels sprouts, cauliflower, chinese cabbage, collards, kale, kohlrabi and of course the common cabbage. Cabbage maggots are harmful to the roots of these garden plants as well as radishes and turnips .
What does it look like?
Hylemya brassicae, the cabbage maggot, is soft-bodied and tends to be a bright to milky white. Cabbage maggots grow to be about 1/3 inch long and can usually be seen in clusters as they feed on the roots of the plants. Cabbage family plant roots which are infested with cabbage maggots will have channels in them and may appear scarred. These areas of the root will either bee slimy or brown and grooved. Typically plants with cabbage maggot damage will begin to show signs of wilting, and then will yellow and die.
How does it manifest?
Cabbage maggots thrive in cook, moist weather and are a primary pest of cabbage family plants in the northern United States due to optimal weather conditions for breeding. Female and male adults are greyish flies which are similar to the housefly, but smaller. Adults of this species also tend to have black stripes down the center of their backs and bristly areas on the back as well. Female adults lay eggs either in the soil surrounding the plants, or on their stems. Within two to three days of laying the eggs, they will hatch into cabbage maggots which promptly tunnel into the roots and stems of nearby plants. Cabbage maggots can tunnel to a depth of 6 inches, getting deep into the root system. As the cabbage maggots feed while they tunnel, damage can open up wounds which increase the risk of plants developing black rot and similar bacterial diseases.
What can you do about it?
If the cabbage family plant has reached the point of wilting, nothing can be done, it will yellow and die. However, you can control cabbage maggots for the next crop by tilling diazinon or pyrifos containing insecticides into the soil between 4 and 6 inches deep prior to planting. This will help prevent damage, but typically the treatment will not last much longer than one month from it's application and it is dependent on the cabbage maggots coming into direct contact with treated areas of soil. You may need to repeat applications, because proper timing is the important issue here. In addition, you can prevent adult females from laying eggs by covering the seedbed with cheesecloth and periodically removing and destroying it.
