YELLOWNECKED CATERPILLARS

 

At least four moth species in the genus Datana may feed as immatures on the foliage of blueberry. These insects are widely distributed throughout the southeastern United States where they feed on a variety of host plants, including apple, cherry, basswood, birch, witch-hazel, and oak (Craighead 1949, Darlington 1952). None of these species are very abundant, but they are likely to cause concern when found on blueberry because of their large size and voracious appetites.

In all four species, the larval stage is a colorful caterpillar that is moderately clothed with long, white hairs. The head is usually black, the neck is narrowly ringed with yellow or orange, and the body is conspicuously marked with longitudinal yellow lines against a black background. Fully grown larvae reach a length of about 5 cm (2 inches). When disturbed, these insects often elevate the anterior and posterior ends of their body, clinging to the substrate by only a few middle pairs of prolegs.

Adults of these caterpillars are light brown moths with a wingspan of 4 to 5 cm (1.5 to 2 inches). The forewings are usually banded with dark brown lines, and the hind wings are somewhat lighter in color than the forewings. Adults are seldom seen because they are active at night.

Illustrations:

  • Larval stage of a yellownecked caterpillar.
  • Feeding aggregation of yellownecked caterpillars.

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    Life Cycle and Seasonal Distribution


    All of these species pass the winter as pupae in the soil. Adults emerge in early summer and lay their eggs in groups of 50 to 100 on the undersides of leaves. After hatching, young larvae often feed together on a single leaf for several days and then gradually disperse to nearby foliage where they continue to feed in loose aggregations. Larvae complete development in late summer, drop to the ground, and pupate under their host plants. There is only one generation per year.

     

    Symptoms and Damage


    Although young Datana larvae only skeletonize the blueberry foliage, older larvae are able to consume entire leaves and may completely defoliate small plants. Extensive feeding may retard growth, but plants are seldom killed because the injury occurs late in the growing season.

     

    Natural Enemies


    Several species of Tachinid flies are known to parasitize yellownecked caterpillars (Craighead 1949). Winthemia datanae is probably the most abundant of these natural enemies. The female flies lay their eggs on host larvae, and the young flies feed internally on host tissues.

     

    Scouting, Management, and Control


    Beginning in mid-sumer, blueberry bushes should be inspected every two weeks. Clusters of older larvae are usually quite visible feeding on the terminal leaves. Since infestations tend to be localized and readily detected in the field, growers can prevent severe defoliation by manually removing the caterpillars, or by destroying the colonies with insecticide from a small, portable sprayer.

    References

  • Craighead, F. C. 1949. Insect enemies of eastern forests. USDA Misc. Publ. #657. 679 pp.
  • Darlington, E. P. 1952. Notes on blueberry lepidoptera in New Jersey. Trans. Amer. Entomol. Soc. 78: 33-57.

    Last updated: 5 June 1997
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