{"id":3335,"date":"2010-11-29T10:26:41","date_gmt":"2010-11-29T15:26:41","guid":{"rendered":"http:\/\/extension.umaine.edu\/ipm\/"},"modified":"2023-01-12T15:06:23","modified_gmt":"2023-01-12T20:06:23","slug":"5005e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/ipm\/ipddl\/publications\/5005e\/","title":{"rendered":"Cabbage Maggots"},"content":{"rendered":"

\n \n \"Print\n <\/a>\n <\/div><\/h3>\n

Pest Management Fact Sheet #5005<\/h3>\n

(Delia radicum)<\/em><\/strong><\/p>\n

James F. Dill, Pest Management Specialist
\nClay A. Kirby, Insect Diagnostician<\/em><\/p>\n

For information about UMaine Extension programs and resources, visit extension.umaine.edu<\/a>.
\nFind more of our publications and books at extension.umaine.edu\/publications\/<\/a>.<\/strong>
\n<\/span><\/strong><\/p>\n

\"cabbage<\/a>Introduction<\/h3>\n

The cabbage maggot (Delia radicum) <\/i>is a very destructive insect that attacks crucifers (cool-weather plants) such as cabbage, broccoli, cauliflower, Brussels sprouts, radishes, rutabagas, and turnips. Wilting leaves are usually a sign of maggot damage and indicate that roots need to be checked for maggots and for damage.<\/p>\n

Description & Biology<\/h3>\n

Cool weather is necessary for the cabbage maggot\u2019s emergence, which takes place over a 2 to 3-week period. This extended period of emergence, added to the lifespan of the fly, exposes seedlings and transplants to a 30-day egg-laying period. There are 3 to 4 generations per year.<\/p>\n

The insect overwinters as an egg-shaped pupa buried in the soil. Flies first emerge and mate during May. The females deposit their eggs at the base of plants. In 3 to 9 days, the white, tapered, legless maggots (larvae) emerge from their eggs. The maggots move to the root zone where they feed, damaging or sometimes destroying the root system. Larvae feed for 20 to 30 days until they are mature (1\/4 to 1\/3-inch long) and ready to pupate. The first spring generation is the most damaging. Adult flies emerge in 10 to 14 days. The flies resemble houseflies, but are 1\/4-inch long with black stripes on the thorax.<\/p>\n

Because of the variation in time of adult emergence in the spring and the variation in length of developmental stages, it is possible for maggots to be present much of the growing season. However, high temperatures and disease suppress populations in July and August. The cooler temperatures of September and October favor development. At that time, the maggots damage fall-maturing plants such as rutabagas, turnips, and Brussels sprouts, as well as other late-season crucifer crops.<\/p>\n\n\t\t