{"id":4346,"date":"2011-01-26T11:37:01","date_gmt":"2011-01-26T16:37:01","guid":{"rendered":"http:\/\/extension.umaine.edu\/ipm\/"},"modified":"2023-03-01T16:15:07","modified_gmt":"2023-03-01T21:15:07","slug":"5006e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/ipm\/ipddl\/publications\/5006e\/","title":{"rendered":"Imported Cabbageworm"},"content":{"rendered":"

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

Pest Management Fact Sheet #5006<\/h3>\n

James F. Dill, Pest Management Specialist
\nClay A. Kirby, Insect Diagnostician
\nCharles D. Armstrong, Cranberry Professional & Staff Entomologist
\n<\/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

Introduction
\n<\/strong><\/span><\/span><\/h3>\n

Imported cabbageworm (Pieris rapae<\/em>) larvae prefer to feed on cabbage, cauliflower, broccoli, Brussels sprouts, turnips, radishes, kale, lettuce and weeds of the mustard family. In fact, this pest is one of the most damaging and destructive enemies of these plants. The caterpillars chew irregular holes in the leaves and usually eat their way into cabbage heads from the bottom. In addition to the feeding damage, the insects\u2019 frass will stain cauliflower.<\/p>\n

Description & Biology<\/h3>\n

The first sign of imported cabbageworm is often the 1\u00bd” butterfly which has yellowish wing undersides but is otherwise white. This stage of the insect emerges early in the spring. The females fly during daylight hours looking for suitable plants on which to lay their eggs. The yellowish, elongated eggs, are laid singly on the underside of leaves.<\/p>\n

In 5 to 7 days, the eggs hatch to become velvety green caterpillars which will grow to 1\u00bd” long. They have a thin yellowish-orange stripe down the middle of the back. It is common for high larval populations in July and August to damage plants so severely that they die or become unmarketable.<\/p>\n

When fully grown, the larva forms a greenish-brown pupa (chrysalis) which can often be found hanging from the bottoms of leaves or other protected areas.\u00a0 Ten days later, the second generation of butterflies emerge, continuing the cycle. There may also be a third generation in Maine. Adults may be seen almost anytime during the summer.<\/p>\n\n\t\t