Cabbage moth

Appearance

For a key to the terms used, see :Glossary of entomology terms.

''B. brassicae'' L. Forewing grey-brown varied with fuscous: lines pale, dark-edged; orbicular stigma rounded, reniform large, white-spotted, or filled in with white; hindwing brownish, with a paler mark near end of vein 2. -
The insect varies in opposite directions; - ab. ''albidilinea'' Haw.
is a blackish form with the reniform stigma and submarginal line white, occurring occasionally in Europe as well as in Britain; — ''scotochroma'' Rob., a local German form, is melanic, with both wings blackish, much like ''albidilinea'', but without the white submarginal line; — ''unicolor'' Tutt has all the markings, dark and light , more or less lost in the fuscous suffusion , the reniform edged only with whitish ; — on the other hand ''andalusica'' Stgr. from Spain is pale grey- brown with a faint ochreous flush, darker grey in female, with all markings obscured except the 3 stigmata which are strikingly pale, with partial blackish outline, especially on their lower edge, the claviform sometimes grey; — ''decolorata'' Stgr. from Issykkul and other localities in Central Asia is pale greyish brown, with the stigmata as in ''andalusica'', but with the markings, especially the submarginal ones, not obsolete; — ''canescens'' Moore from Yarkand, which I have not seen, is, judging from the figure, very close to, if not identical with, ''decolorata'' which it antedates by 10 years. Larva polyphagous, varying in ground colour from green to brown and blackish, with broad pale spiracular line; a dorsal hump on segment 11.

Behavior

Adults emerge from the end of April through the beginning of June. Shortly after emerging, the adult moths mate, as discussed in more detail in the mating section. The moth is most active at night, when it flies between plants and feeds. During the day, the adult moth seeks cover under the foliage of surrounding plants.

Reproduction

Upon oviposition, the eggs are pale white, oblong, hemispherical, and ribbed. The eggs also develop a brown marking at their center. The egg typically measures 1.2 mm in diameter and hatch within six to ten days.

Food

Here is a list of the known and recorded food plants for ''Mamestra brassicae'':
⤷ ''Allium'' – onion
⤷ ''Aquilegia'' – columbine
⤷ ''Beta'' – beet
⤷ ''Brassica''
⤷ ''Bryonia'' – bryony
⤷ ''Calendula'' – marigold
⤷ ''Cannabis'' – marijuana
⤷ ''Chrysanthemum''
⤷ ''Cucurbita''
⤷ ''Dianthus'' – carnation
⤷ ''Helianthus'' – sunflower
⤷ ''Hyoscyamus'' – henbane
⤷ ''Hyssopus'' – hyssop
⤷ ''Lactuca'' – lettuce
⤷ ''Linum'' – flax
⤷ ''Lychnis'' – Maltese cross
⤷ ''Lycopersicon'' – tomato
⤷ ''Malus'' – apple
⤷ ''Nicotiana'' – tobacco
⤷ ''Pisum'' – pea
⤷ ''Plantago'' – plantain
⤷ ''Raphanus'' – radish
⤷ ''Rheum'' – rhubarb
⤷ ''Rudbeckia''
⤷ ''Rumex''
⤷ ''Silene''
⤷ ''Solanum'' – potato
⤷ ''Spinacia'' – spinach
See Robinson, G. S. et al.

Migration

A study of ''M. brassicae'' in East Asia demonstrated that the species is migratory. Researchers found that annual migration across a 40–60 km strait. Data also indicates that females migrate more than males, with a significantly higher proportion of captures being female compared to the population sex ratio during the months of May to September. Coupled with the finding that these migratory females had high ovarian development and mating rate during this time, researchers concluded that this migration promoted female sexual maturation prior to mating. This would allow females to mate and oviposit in their newly arrived upon territories.

Evolution

The life history is highly variable depending on the location of the population. Some populations are able to fit two to three generations within one calendar year. Other populations, in less favorable climates, may have only one generation in a given year. Diapause is this species' most variable life stage, lasting anywhere from 80 days to six months if needed over the winter.