Appearance
While crucifers are preferred, over 160 plants can serve as hosts for the cabbage looper larvae. The adult cabbage looper is a migratory moth that can be found across North America and Eurasia, as far south as Florida and as far north as British Columbia. Its migratory behavior and wide range of host plants contribute to its broad distribution.The cabbage looper larva is a minor vegetable pest, especially for crucifers. While it is not significantly destructive, it is becoming difficult to manage due to its broad distribution and resistance to many insecticides. Numerous methods are being researched in order to control this species.
Distribution
The cabbage looper can be found across North America and Eurasia, as far south as Florida and as far north as British Columbia.Cabbage looper populations in North America migrate from Mexico to Canada, depending on the seasons. It generally overwinters in Mexico or southern California, where temperatures are above 16 °C even during winter. It used to be frequently found in Florida, but this has lessened due to fewer cabbage crops. As northern regions of North America grow warmer, the cabbage looper gradually moves upward, only migrating if the region is above 16 °C. During summer, it is less commonly found in southern regions, due to high temperatures. Similar to the monarch butterfly, populations presumably migrate in groups, as there is little genetic difference between source and migrating populations.
Similar seasonal distributions were found in Europe. There, the cabbage looper can be found from England to southeastern Europe.
Reproduction
Cabbage looper larvae are a type of cabbage worm, green in colour with a white stripe on the side. After hatching, they are green and slightly hairy, but eventually turn green and lose the hair, leaving only a few bristles. They are identified by their looping behaviour, in which they arch their body in a loop when they crawl. Larvae are generally 3–4 cm long, and can have four to seven instars within 9–14 days. Larvae initially do not consume much food but increase their consumption during their lifetime until they are consuming three times their weight daily.Cabbage loopers detect plant odors to locate food resources and suitable host plants for laying eggs, thereby increasing their chances for survival and reproduction. Mated females respond faster to plant odors compared to their unmated female and male counterparts. This difference in response time may be a result of mated females needing host plants for both food and egg laying whereas unmated individuals mostly use host plants for food, so mated females have greater motivations to find a host plant. The cabbage looper is attracted to the floral compounds:⤷ phenylacetaldehyde
⤷ methyl salicylate
⤷ 2-phenylethanol
⤷ benzaldehyde
⤷ benzyl alcohol
⤷ benzyl acetate
⤷ methyl-2-methoxy benzoate
Although the strongest attractor is phenylacetaldehyde, the cabbage looper is more attracted to a blend of odors than phenylacetaldehyde alone.
Predators
General predators like spiders, ants, and lady beetles prey on cabbage looper eggs and larvae, removing 50% of the eggs and 25% of the larvae within three days. Lady beetles consume at the highest rate. Other common predators of cabbage looper larva include "Orius tristicolor, Nabis americoferus," and "Geocoris pallens."Migration
The cabbage looper can be found across North America and Eurasia, as far south as Florida and as far north as British Columbia.Cabbage looper populations in North America migrate from Mexico to Canada, depending on the seasons. It generally overwinters in Mexico or southern California, where temperatures are above 16 °C even during winter. It used to be frequently found in Florida, but this has lessened due to fewer cabbage crops. As northern regions of North America grow warmer, the cabbage looper gradually moves upward, only migrating if the region is above 16 °C. During summer, it is less commonly found in southern regions, due to high temperatures. Similar to the monarch butterfly, populations presumably migrate in groups, as there is little genetic difference between source and migrating populations.
Similar seasonal distributions were found in Europe. There, the cabbage looper can be found from England to southeastern Europe.
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