﻿132 SEVENTH ANNUAL REPORT 



Finally, to sum up the differences between the two species, besides the structural 

 and more reliable characters already given, in ji^eneral terras, spretus compared tO' 

 femur-riibrum, may be distinguished by the following less reliable and more inconstant 

 characters : It is the larger species ; the antennae are sliglitly shorter and paler ; the 

 occiput and two anterior lobes of the prothorax are more livid and darker ; tlie third 

 lobe of prothorax broader; the dark, subdorsal, prothoracic mark running from the 

 eyes less pronounced ; the oblique, yellow line from base of wings to base of hind 

 thighs more often obsolete; the front wings paler toward tips, more ferruginous at 

 base, with larger, more conspicuous spots ; the anal abdominal joint of male also much 

 paler ; the cerei and valves in the female generally shorter and more robust. 



Such are the distinguishing features between these two insects, when the more 

 typical specimens of the western spretus are compared with femur-ruhrum as it occurs 

 around St. Louis. That these distinguishing features will lose their value in propoi"- 

 tion as abundant material from all parts of the country is examined and compared, I 

 have not the least doubt ; for I have already shown that such is the fact so far as color- 

 ation and length of wing is concerned, and the meagre material Avhich I have Ironi 

 the East indicates considerable variation and approach in the more important structu- 

 ral characters. h\ considering the ravages of migratory locusts in the Atlantic States.^ 

 I shall recur to this subject. 



CHRONOLOGICAL HISTORY. 



The plague of locusts is as old, nay older, than the Bible, where, 

 in Exodus, we are told how they went up over the land of Egypt and 

 " covered the face of the whole earth, so that the land was darkened ; 

 and they did eat every herb of the land, and all the fruit of the trees 

 which the hail had left ; and there remained not any green thing in 

 the trees, or in the herbs of the field, throughout all the land of 

 Egypt."* Faulus Orosius tells us that in the year of the world 3,800, 

 such infinite myriads of locusts were blown from the coast of Africa 

 into the sea and drowned, that, being cast upon the shore, they emit- 

 ted a stench greater than could have been produced by the carcasses 

 of one hundred thousand men, and caused a general pestilence.f 

 Numerous, indeed, are the accounts of general devastation, pesti- 

 lence and famine that have frequently followed in the wake of these 

 locusts in the East, and travelers in South Africa, Asia and South 

 Europe, have left us abundant records of the fearful devastations of 

 this " Army of the Great God," as the Arabs term these migrating, 

 hosts. Their history is one of dire calamity and desolation ; and their 

 devastations have become part of the history of nations : they have 

 even been perpetuated in coins. Those who have the curiosity to 

 acquaint themselves with the history of locusts in the more ancient 

 parts of the world, cannot do better than refer to Kirby and Spence,^ 



•Exodus, X, 15. 



t Oros, Contra Pag, 1, V., c. 2. 



X Introduction to Ent. I. , Letter VII. , London, 182S. 



