Southern White Ascia monuste Linnaeus Lepidoptera Pieridae

Natural History

Distribution. Southern white resides in Florida, the Gulf Coast areas of the southern states, southern Texas, Mexico, and most of Latin America. This butterfly exhibits strong migratory tendencies, moving northward in the summer and southward in the winter, but in North America it rarely becomes numerous anywhere other than subtropical, coastal areas. They are more dispersive under high-density conditions.

Host Plants. Larvae feed on plants in the families Cruciferae, Bataceae, Capparidaceae, and Tropaeola-ceae. Principal hosts are saltwort, Batis maritima, in coastal regions and pepperweed, Lepidium virginicum, elsewhere. Vegetables fed upon are cabbage, cauliflower, collards, kale, radish, and turnip. Other food plants include beach cabbage, Cakile maritima; spider flower, Cleome spinosa; clammy weed, Polanisia sp. nasturtium, Tropaeolum majus; and others. Adults frequent a variety of flowering plants to obtain nectar.

Life Cycle and Description. The number of generations is poorly documented, but at least three are known annually, and adults are active year-round in southern Florida and Texas. Reproductive diapause likely occurs during the winter months.

  1. The eggs are pale-yellow, elongate, and bear 11 longitudinal ridges. They may be laid singly, in small groups, or in cluster of up to 50, depending on the host. On average, eggs are laid in clusters of 16 on young leaves. The female may deposit 800-1000 eggs over the course of her life, which is typically 8-10 days in duration.
  2. Young are often gregarious, and such larvae grow faster than solitary individuals. Larvae are mottled gray or brownish green, often with a purplish hue, and bear five longitudinal orange or yellow-green bands running the length of the body. Rows of black spots also occur laterally. The head is yellow and orange, and marked with black spots. The larva attains a length of about 3-4 cm. A key for differentiating this caterpillar from other crucifer-feeding pierids is provided in Appendix A. (See color figure 95.)
  3. The chrysalis is ivory white with numerous black markings, and bears one orange-yellow band dorsally, and another on each side. The general shape is similar to that of imported cabbage butterfly, but the projections are greatly blunted in the southern white, and appear to be nothing more than large bumps. The length is about 2.5 cm.
  4. The adult has a wingspan of about 6-8 cm. The male butterfly is almost pure white dorsally, but has a black, deeply indented band along the distal edge of the front wing. On the underside of the male, the hind wings are tan, as are the tips of the front wings. The female has two rather distinct color forms. The long-lived winter form is principally white, but with wider black bands than the male, and a single black spot on the forewings. During the summer months, the female is much darker, brown to dark-gray; such butterflies tend to have a broader dark band on the forewings, but less scalloping of the band. Caterpillars raised under short-day conditions produce the dark adult form. A key for differentiating this
Adult male southern white.
Adult female southern white.

species from other cabbage white butterflies is included in Appendix A. (See color figure 201.)

The biology of southern white was given by Opler and Krizek (1984) and Scott (1986).

Damage

Larvae feed on foliage, and eat small and large holes in leaves. In coastal areas they sometimes defoliate small plantings.

Management

Hayslip et al. (1953) considered southern white to be a minor pest in Florida. Management techniques appropriate for imported cabbageworm should be suitable for this insect also.

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