Circular No. 1 32. 



Issued February 13, 1911. 



United States Department of Agriculture, 



BUREAU OF ENTOMOLOGY. 

 L. O. HOWARD, Entomologist and Chief of Bureau. 



THE PERIODICAL CICADA IN 1911. 



( Tihicen septendecim L. ) 



By C. L. Marlatt, 

 Entomologist and Assistant Chief of Bureau. 



INTRODUCTION. 



Two important broods of the periodical cicada (fig. 1) will appear 

 this vear. One of these belongs to the 17-year race and extends from 

 New York southward into North Carolina, in general lying east of the 

 Allegheny Mountains. 

 The other is one of the 

 largest brood of the 

 southern, or 13-year, 

 race and covers the 

 lower half of the Ms- 

 sissippi Valley. Both 

 of these broods have 

 been very well studied 

 in past years, and their 

 distribution has been 

 satisfactorily and in the 

 main probably accu- 

 rately determined. 

 The approacliing reap- 

 pearance, however, of these broods of the cicada is already leading to 

 inquiries, and this circular is issued to meet such inquiries, and also 

 for the purpose of securing reports of occurrence to add to the present 

 knowledge of the distribution of these broods. 



17-YEAR BROOD II, 



This brood, in the main, occupies territory immediately east of 

 Brood I — a scattering brood appearing in 1910. Its exact range is 

 shown on the accompanying map (fig. 2), the black dots indicating 

 records by counties only of the appearance of the insect in former 

 years at the regular 1 7-year intervals. In many cases we have numer- 



FiG. 1. — The periodical cicada (Tibicen septendecim): a, Adult; b, 

 same, side view; c, shed pupal skin. (Author's illustration.) 



