New Pest Response Guidelines - aphis - US Department of Agriculture

Identification
Similar Species
In the United States the PTL can be easily confused with a number of
Lasiocampidae and Lymantriidae moths, for example, the gypsy moth
(Lymantria dispar), the Eastern tent caterpillar (Malacosoma americanum,
Fabricius), Western tent caterpillar (M. californicum (Packard)), Pacific tent
caterpillar (M. constrictum (H. Edwards)), Southwestern tent caterpillar (M.
incurvum (H. Edwards)), White satin moth (Leucoma salisis L.) and the
Douglas-fir tussock moth (Orgyia pseudotsugata McDunnough). In addition to
morphological differences, these moth species show clear ecological
differences. None of them, with the exception of the Douglas fir Tussock moth,
feeds on conifers and except for the Douglas-fir tussock moth, they all lack the
white spot on the front wing that is characteristic of several species of
Dendrolimus. None of the larvae of these species have the distinctive white
band between two dark blue or black bands on the thorax and the V shaped
marks on the dorsal part of the last abdominal sections (Figure 3-13 on page
3-16).
The Douglas-fir tussock moth (O. pseudotsugata McDunnough) can be
distinguished because the adults are much smaller than the adult PTL (30 mm)
and darker. Two white spots on the forewings can clearly confuse this moth
with the PTL moth, however, the white spots are positioned at the distal edges
and not the proximal or basal portion of the front wing (Figure 3-13 on page
3-16). The spots in Dendrolimus moths are located closer to the moth body.
The larva of the Douglas-fir tussock moth have two long, dark tufts resembling
12/2012-01 Dendrolimus Pine Moths 3-15