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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
(Blissus leucopterus Say) and the Colorado Potato-beetle (.Leptinotarsa 
decemlineata Say). The degree and extent of the damage that certain 
native insects may inflict upon native and economically unimportant 
plants, however, is not so well known to entomologists, and some ob¬ 
servations along that line, dealing with the apparent extinction of a local 
plant species and the relation of this to the behavior of the depredating 
insect in another respect is, therefore, worthy of record. The observa¬ 
tions were made in Somerset County, New Jersey, where one or the 
other of the writers was engaged, during the summers of 1921, 1922 and 
1923, upon insect parasite studies for the U. S. Bureau of Entomology. 
The species of plant involved is the leguminous annual Crotalaria 
sagittal is L. (commonly known as Rattle-box) which ranges, chiefly 
along the coast, from eastern Massachusetts and southern Vermont to 
Florida and Texas, and northward in the Mississippi basin to Indiana 
and South Dakota (Gray, 1908). In Massachusetts, according to 
Professor M. L. Fern aid of the Gray Herbarium, Harvard University, 
it is found invariably on sandy beaches of ponds, and in wet seasons 
may be “drowned out.” In New Jersey, however, the stands or stations 
of the plant—those that were under observation at least—were in dry 
and open places quite removed from bodies of water and extended, 
respectively, over approximate areas of 5, 80 and 175 square rods. 
The insect concerned was the Arctiid moth Utetheisa bella L., which 
occurs throughout the Atlantic States, in this country, and in parts of 
Canada, the larvae of which are reported by Packard (Fifth Rept., 1890) 
and by Smith (N. J. Insects, 1909) as feeding on cherry, elm, Mvrica, 
Lespedeza and Crotalaria. The writers, however, have found the larvae 
only on Crotalaria sagittalis , although some of the other reported food 
plants were present in the localities. ) 
The caterpillars were first observed July 20, 1922, and by August 19, 
about one month later, they were very numerous, as were also the 
moths. Some idea of the large numbers of larvae present may be had 
from the fact that although large numbers of them were collected be¬ 
tween August 19 and 24, thousands were still present on the latter date, 
and as the Crotalaria was now exhausted, they were engaged in an 
apparently fruitless search for food. This condition obtained, roughly, 
in each of the three widely separated localities. In no instance, in the 
case of the food plant, as far as could be observed, did pod-formation 
and seed-setting take place. The following summer, that of 1923, no 
Crotalaria could be found on any of its three former sites. The insect 
