Hellula phidilealis Walker Lepidoptera Pyralidae
Distribution. Cabbage budworm is a tropical insect. It is a common pest of cabbages in the Caribbean and in Central and South America, and also occurs in West Africa. In the United States, it occurs in Florida, Texas, Arizona, and Hawaii.
Host Plants. Budworm attacks several crucifer crops, including cabbage, cauliflower, Chinese cabbage, radish, and turnip.
Natural Enemies. This insect has not been well studied, and few natural enemies are known. The parasitic fly Nemorilla maculosa Meigen (Diptera: Tachini-dae) is reported to parasitize budworm.
Life Cycle and Description. Total generation time of cabbage budworm is about 30 days, and it breeds continuously in tropical areas, including southern Florida.
- The eggs are deposited singly or in small clusters, often along the leaf midrib. The oval eggs are white when first deposited, but soon turn brown, and hatch in about three days. They measure about 0.5 mm in diameter, and bear a longitudinal ridge. The female produces 3-4 egg clusters, producing eggs at about 16 per day over a period of about five days. Total egg production averages about 65 per female, but may reach 160 per female.
- Newly emerged larvae feed initially on the lower surface of the leaf, and then tunnel into a petiole or leaf vein. Frass is ejected from the entrance hole as the larvae feed. Feeding tunnels are lined with silk threads. The larval developmental period averages about 16 days. There usually are six instars, with average development times of 4.2, 2.2, 2.9, 2.1, 2.3, and 5.6 days, respectively. Larvae are creamy white with three reddish-brown longitudinal stripes dorsally. At maturity, they measure about 10-14 mm long. The head capsule is black. About two days before pupation the larvae cease feeding and spin a whitish silken cocoon, and pupate within.
- Pupation may occur on the plant, near the exit hole, or nearby in the soil. The pupa is about 9 mm long, yellow-brown in color, and covered with a gray waxy secretion. The pupal period is about 10 days.
- Adults are dimorphic. The males are dark brown with an undulating wavy fringe on the fore-wings, whereas the females are light brown and lack the fringe. The hind wings are whitish, becoming darker at the margins. The moths are quite similar in appearance to cabbage webworm, Hellula rogatalis (Hulst), but they lack the yellowish tint on the fore-wings. Adult longevity averages 10 days, and the moths are nocturnal.
The biology of cabbage budworm was given by Cadogan (1983) and King and Saunders (1984).
Larvae bore into leaf stalks, stems, and the growing points of plants. Destruction of the growing point causes the plant to produce several small heads rather than one large one; these small heads have no commercial value. Damage to stems results in stunted plants. It is considered to be a serious pest in parts of the Caribbean, but elsewhere it is only occasionally important. It is a pest of small plots and gardens, particularly at low altitude.
Effective insecticidal control, including use of Bacillus thuringiensis, requires good penetration into the foliage canopy. As insects quickly bore into plant tissue, it is important to treat before the infestation becomes severe. Sanitation also is very important. Many problems stem from crop residues or volunteer plants, especially Chinese cabbage.
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