Host: Ponderosa pine
Newly hatched pine butterfly larvae are gregarious feeders
on older foliage and then move to the new foliage as they mature.
Mature larvae are approximately 2.5 cm long, dark green in color
and have light green heads. The body is covered with fine hairs
and has two white lateral stripes on the side. Adult moths are white
with black markings.
Adults fly and lay their green eggs from August through October.
The eggs overwinter and the larvae hatch the following June or about
the time new foliage appears. The small larvae feed in clusters
with their black heads oriented toward the tip of the needle. As
the larvae mature they feed singly. They pupate in late July for
approximately 15-20 days.
Effects: This insect has caused spectacular
defoliation in the Pacific Northwest, however, it causes little
defoliation in the Southwest.
Insects and Diseases: The pine butterfly adult resembles
the common cabbage butterfly. In addition, the young larvae feeding
in groups may be confused with other gregariously feeding larvae
such as sawflies. These would
include Neodiprion spp. and Zadiprion spp. of
sawflies. Pandora moth is also a defoliator of ponderosa pine. This
insect has a 2-year life cycle. Mature larvae are distinctly larger,
brown to yellowish green in color and possess stout, branched spines
on each body segment.