Pine webworm

Pococera robustella (Zeller) (Lepidoptera: Pyralidae)

Orientation to pest

Pine webworm, Pococera robustella (Zeller), is a native North American moth. Females lay groups of one to 10 overlapping eggs on host needles. Young larvae are pine needle miners, but older larvae feed externally, building webs around groups of needles. Larvae leave the nest to clip needles, which they bring back into the nest to consume. Mature larvae move to the ground and spin cocoons in which they pupate. Several species of pines are attacked. In southern slash pine (Pinus elliottii Engleman) plantations, damage occurs mainly in the first year after planting. In northern parts of the United States, damage occurs in jack (Pinus banksiana Lamb.) and red pine (Pinus resinosa Sol. ex Aiton) plantations, but is mostly of concern to Christmas tree growers due to the unsightliness of the webs. There are one (in the north) to three (in the south) generations per year.

Hosts commonly attacked

In North America, this moth attacks many pine species but is most common on slash (P. elliottii), red (P. resinosa) and jack (P. banksiana) pines.

Distribution

This moth occurs in southern Canada and throughout most of the eastern United States.

Images of pine webworm

Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org 768x512 / 1536x1024	Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org 768x512 / 1536x1024	Robert L. Anderson, USDA Forest Service, Bugwood.org 768x512 / 1536x1024	Robert L. Anderson, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Figure 1. Adult pine webworm, Pococera robustella	Figure 2. Larva of pine webworm	Figure 3. Feeding web of larvae of pine webworm	Figure 4. Damage to a young pine seedling caused by pine webworm

Important biological control agents related to this pest species

The ichneumonid Syzeuctus elegans (Cresson) is a common parasitoid of this species. Other natural enemies include other parasitic wasps, parasitic flies, predatory insects and birds.

Web links for information on pine webworm

• Featured Creature Fact Sheet | University of Florida and FDACS
• BugwoodWiki Article | wiki.bugwood.org
• Entomology Circular | FDACS Division of Plant Industry

Articles

• Hertel G. D. and D. M. Benjamin. 1979. Biology of the pine webworm in Florida slash pine plantations. Annals of the Entomological Society of America 72: 816-819.
• Wallesz, D.P. and D. M. Benjamin. 1960. The biology of the pine webworm, Tetralopha robustella, in Wisconsin. Journal of Economic Entomology 53: 587-589.