COLONIZATION OF THE NORTHEASTERN 
UNITED STATES BY TWO PALEARCTIC MOTHS 
(LEPIDOPTERA: TORTRICIDAE) 
By Jerry A. Powell 1 and John M. Burns 2 
Thirty years ago, two Palearctic tortricids, Croesia forskaleana 
(Linnaeus) and Clepsis unifasciana (Duponchel), were recorded in 
the Nearctic from Long Island, New York (Klots 1941). Almost 
no information on their progress has been published, but specimens 
subsequently collected on another island and at several points on the 
mainland indicate that these immigrants are spreading. Because 
rapid range changes are potentially useful in analyzing microevolu- 
tion (see, e.g., Baker and Stebbins 1965; Burns 1966) — the more 
so as they are accurately documented — • we attempt here to put the 
scene together, to interest other workers in future developments, and 
to encourage accelerated deposition of specimens in institutional 
collections. 
Although numerous lepidopteran and other insect species have 
reached the United States from the Old World and become estab- 
lished (e.g., Popham and Hall 1958), many came so early, or were so 
unspectacular after arriving, that their American history is obscure. 
The rare detailed accounts of spread deal with species such as the 
gypsy moth, Porthetria dispar (Linnaeus) (Corliss 1952), and the 
spotted alfalfa aphid, Therioaphis maculata (Buckton) (Smith 
1959), which are conspicuous or economically important (or both). 
A few introductions of Microlepidoptera have been fairly well 
chronicled, such as that of the tortricid Cnephasia longana 
(Haworth) on the Pacific Coast (Powell 1 964*2) ; but most have 
not. At worst, as in California populations of the fungus-eating 
Oinophila v-flava (Haworth), a long gap in the temporal record, 
together with complex ecological and distributional data from the 
present, make an unequivocal choice between native and alien status 
impossible (Powell 1964^; Lawrence and Powell 1969). The 
crucifer-eating diamondback moth, Plutella maculipennis (Curtis), 
and various cosmopolitan household pests like the Indian meal moth, 
Plodia inter punctella (Hiibner), and the clothes moth, Tineola 
biselliella (Hummel), have been in North America so long that 
neither their beachheads nor their invasion patterns are known. Even 
1 University of California, Berkeley. 
2 Museum of Comparative Zoology, Harvard University. 
Manuscript received by the editor April 29, 1971. 
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