{"id":331,"date":"2017-08-11T12:57:22","date_gmt":"2017-08-11T20:57:22","guid":{"rendered":"http:\/\/blogs.oregonstate.edu\/vegnet\/?page_id=331"},"modified":"2021-07-29T10:37:52","modified_gmt":"2021-07-29T18:37:52","slug":"imported-cabbageworm","status":"publish","type":"page","link":"https:\/\/agsci-labs.oregonstate.edu\/vegnet\/pest-profiles\/imported-cabbageworm\/","title":{"rendered":"Imported Cabbageworm"},"content":{"rendered":"
\n \"\"\n
Greenworms detected in a garden in NE Portland, 12-May, 2020.<\/figcaption>\n <\/figure>\n

Imported Cabbageworm <\/strong>(Pieris rapae<\/em>) (Lepidoptera: Pieridae)<\/p>\n

Also known as the small cabbage white butterfly (adult), or greenworm (larvae).<\/p>\n

Identification and Life Cycle  <\/strong>Adult butterflies are white, and about 30-50mm. The front wing has a dark ‘corner’, plus black circular dots (males have 1 spot, females have 2). There are at least 2 broods, but continual development has been noted in California.<\/p>\n

Small larvae are pale green with a yellow dorsal stripe (on their back). As larvae mature, they develop a fuzzy appearance and retain the yellow stripe, although it may appear broken in spots. Yellow markings also occur along the sides.<\/p>\n

Pupae are ornate (see photo below), with keeled projections and orange coloring. One should become familiar with pupal ID because this is the overwintering stage.<\/p>\n

Damage<\/strong><\/p>\n

Damage can be extensive, and appears similar to slug damage. Leaf margins are defoliated first, and if left unchecked, plants can be reduced to nothing but stems and midribs. <\/p>\n

On older plants, tunneling into heads is common. This species produces a large amount of wet, greenish fecal pellets which can cause rejection of commercial cauliflower heads.<\/p>\n

Monitoring<\/strong><\/p>\n

\"pierisAdults are not very active during cloudy or breezy days, and a commercial pheromone is not available. Because of this, monitoring for this species is difficult, especially in the PNW<\/u>.<\/p>\n

The butterflies have a distinct, erratic flight which may help you see them in the landscape. They usually fly low above brassica fields or weedy borders (see video).<\/p>\n

Do not spray for adult butterflies. If many adults are seen fluttering about, return in a few days and scout. Closely examine leaves for rocket-shaped eggs laid singly. Small larvae tend to prefer leaf undersides.<\/p>\n

Consult the PNW Handbook<\/a> for more information and current management recommendations.<\/p>\n\n\t\t