THE LOCUSTS PROPER. 175 



are transparent, with a very pale greenish-yellow tint next 

 to the body, and are netted with brown lines. The hind- 

 most thighs have two large spots, on the upper side, and the 

 extremity, black ; but are red below, and yellow on the in- 

 side. The appendages at the tip of the body in the male 

 are of a long triangular form. Length from J inch to 1 

 inch; exp. lj to If inch. 



The red-legged locust was first described by De Geer from 

 specimens sent to him from Pennsylvania, and I have re- 

 tained the scientific name which he gave to it. It is the 

 Gryllus (Locusta) erythropus of Gmelin, and the Acrydium 

 femorale of Olivier. It appears to be very generally diffused 

 throughout the United States, and sometimes so greatly 

 abounds in certain places as to be productive of great injury 

 to vegetation. I have already described its prevalence on 

 our salt-marshes ; and it seems to constitute those large mi- 

 grating swarms whose flight has been observed and recorded 

 in various parts of this country. It comes to maturity with 

 us by the latter part of July ; some broods, however, a little 

 earlier, and others later. It is most plentiful and destructive 

 during the months of August and September, and does not 

 disappear till some time in October. 



II. Locusta. Locusts Proper. 



With the English entomologists, I apply the name Locusta 

 to that genus which includes the celebrated migrating locust, 

 or Gryllus Locusta migratoria of Linnasus. By the older 

 French entomologists the insects contained in it were united 

 to the genus Acrydium; but Latreille afterwards separated 

 them from Acrydium under the generical name of (Edipoda 

 (which means swelled leg), and he is followed in this by 

 Serville, the latest writer on the Orthoptera. In the in- 

 sects of this genus the breast is not armed with a blunt 

 spine or tubercle, a character which distinguishes the genus 

 Acrydium from it. In other respects these two genera are 

 much alike. 



