32 NEW YORK STATE MUSEUM 
Larvae of the genus Pyrausta resemble one another so closely that 
it is not easy to distinguish between related forms. This is partic- 
ularly true of the smartweed borer, Pyrausta ainsliei Hein, 
a species occurring rather commonly in smartweed and frequently 
when nearly full-grown forsaking its food plant and entering nearby 
herbaceous plants, among others, corn. It is consequently very 
desirable to be able to distinguish between this casual invader of 
corn and the very similar and much more injurious European corn 
borer. 
The full-grown European corn borer is moderately stout, the middle 
of the body being distinctly thicker than the extremities and the 
head brown or reddish brown, rarely black. The submedian tubercles 
on the anterior portion of each yellowish gray abdominal segment, 
specially the first to the sixth, are almost invariably rather widely 
separated, the distance being usually decidedly greater than the 
diameter of the tubercle. The anal plate is rather distinctly angulate 
laterally and has the anterior border somewhat emarginate mesially 
and laterally. An apparently invariable characteristic is found in 
the location of anterior setae 2 on the head, in that it is located on or 
close to a straight line drawn from anterior setae 1 to the anterior 
puncture. 
The full-grown larvae of the smartweed borer is distinctly more 
slender than that of the European corn borer and with very little 
if any thickening near the middle of the body. It has a very dark- 
brown or black head and the whitish body is apparently more 
spotted, due to the submedian tubercles on the anterior portion of 
the abdominal segments, specially 1 to 6 being rather larger and there- 
fore closer to each other, the distance between them being usually 
distinctly less than the diameter of a tubercle. The anal plate is 
not distinctly angulate laterally and the anterior margin is nearly 
truncate and slightly convex laterally. In this borer anterior setae 
2 of the head is distinctly outside or lateral of a straight line drawn 
from anterior setae 1 to the anterior puncture. This smartweed 
borer is an accidental invader of corn stalks, and is not known to 
cause the injury so generally associated with the European corn 
borer larvae. 
Manner of spread. Fortunately the moths do not fly great dis- 
tances or the infested area would have been considerably larger after 
several seasons of nearly unchecked breeding. The pest can be 
widely disseminated by the shipment of infested plants or parts 
of plants, notably corn cobs, corn stalks, and in summer green corn 
as well as in a number of garden products, specially celery, Swiss 
