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, com. It is consequently very 

 desirable to be able to distinguish between this casual invader of 

 com and the very similar and much more injurious European com 

 borer. 



The full-grown European com 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 i to the anterior 

 puncture. 



The full-grown larvae of the smartweed borer is distinctly more 

 slender than that of the European com 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 i 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 i to the anterior puncture. This smartweed 

 borer is an accidental invader of com stalks, and is not known to 

 cause the injury so generally associated with the European com 

 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 com cobs, com stalks, and in sunmier green com 

 as well as in a number of garden products, specially celery, Swiss 



