may group upwards of 350 eggs together on the underside of a leaf. Females lay around 2500 eggs after copulation. Eggs are generally laid from May to June, but there is variation between populations of the moth. The eggs hatch within five to twelve days. The incubation period is highly dependent on environmental factors, mainly temperature. The incubation ranges from six days at 25 °C to 12 days at lower temperatures. Oviposition behavior has been studied comparing three different host plants: cabbage, tomatoes, and chrysanthemums. Females landed most often on tomato plants, but spent the most time on cabbage plants. Further, females were able to lay eggs more rapidly on cabbage plants and spent more time dragging their ovipositors on the leaves of the tomatoes before depositing their eggs. While the significance of these findings may not be fully understood, it demonstrates a keenness towards cabbage plants as preferred hosts for oviposition and that females must gauge host plant quality before depositing eggs on a given leaf. Preferences for plant species is also demonstrated, since few eggs were laid on chrysanthemums. Another study was conducted to understand the influence of host plant damage on the host-finding behavior of female moths. Surprisingly, female moths of this species tend to preferentially select for damaged host plants for oviposition. This finding is rather surprising given that it would be expected that females would select for undamaged plants to help her offspring avoid resource competition with whatever species had already fed on the plant. However, researchers hypothesize that this may be due to the release of volatiles, to which females are attracted. 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. As a pest The caterpillars are particularly damaging from the first to the fourth instars. During the first three instars, the larvae feed gregariously and may skeletonize the leaves upon with they