THE NEARCTIC BUD WORMS OF THE LEPIDOPTEROUS 

 GENUS HELIOTPHS 



By S. E. Crumb 



Of the Bureau of Entomology, United Slates Department of Agriculture 



Larvae of the genus Heliothis Ochsenheimer have a marked fond- 

 ness for the buds, young leaves, and developing fruits of plants and 

 for this reason have been given the name of budworms. The best- 

 known species is the corn earworm, bollworm, or false tobacco bud- 

 worm (Heliothis ohsoleta Fabricius). According to Bishopp,* the 

 daniage caused by this species may be conservatively estimated at 

 $30,000,000 annually. Another important species is the tobacco 

 budworm {Ueliothis vircficens Fabricius), which is a well-known pest 

 of tobacco. 



No satisfactory means of distinguishing the species of larvae in 

 this genus has been provided up to the present, since coloration has 

 been depended upon for this purpose and the coloration is extremely 

 variable. Structural characters are provided here by which the 

 species may be positively determined. 



GENERIC CHARACTERS 



Examination of the four species of Heliothis larvae described in 

 the following pages has disclosed the following characters common to 

 the group, which may be considered provisionally as generic charac- 

 ters. It will be noted that the skin is clothed with minute spinules; 

 setae IV and V on the pro thorax are in a horizontal plane; and the 

 third joint of the labial palpus is but little if any longer than the 

 second. This combination of characters will serve to distinguish 

 this group from any other larvae known to the writer. 



White or yellowish, usually broken, longitudinal lines on the body 

 middorsally, dorsed to setigerous tubercle I, between tubercles I and 

 II, and at the upper margin of the supraspiraciilar area. Skin clothed 

 with minute spinules. Setigerous tubercles IV and V on the pro- 

 thorax (on prespiracular shield) in a horizontal plane (fig. 14). 

 Spinneret long and slender, about 5 times or more as long as the 

 median breadth and tapering somewhat toward the apex (fig. 

 6). Labial palpus with the third segment but little if any longer 

 than the second segment (fig. 5). - Blade of the maxillulae with 



> Bishopp, F. C. The Bollworm or Corn Earworm. Farmers' Bull. 872, U. S. Dept. Agr., p. 3, 1922. 



No. 2617.— Proceedings U. S. National Museum, Vol. 68. Art. 16 



61370— 26t 1 



