57 



NUMBER OF ANNUAL BROODS. 



The number of broods which this insect produces in one season 

 has been a subject of considerable discussion for the past twenty 

 years, and the question has not, up to the present writing, been set- 

 tled with perfect satisfaction to all parties concerned. Profs. Eiley 

 and Walsh, and with them several other writers, maintained that it 

 was single-brooded, and favored the theory of hibernation in the 

 imago or moth state. Prof. Thomas, on the other hand, believed 

 that it was double-brooded, and favored the theory of hibernation 

 in the chrysalis state. 



In the preceding pages I have given an account of two successive 

 broods of these insects and a partial account of a third. As the 

 latter were young worms, taken as late as the month of November, 

 there can be no doubt that they will hibernate in their present 

 state, finish their growth in the early part of the following spring, 

 and be changed to moths in the months of April or May following. 

 I have obtained moths of a closely allied species — the Leucania 

 phragmatidicola of Guenee — in the latter part of May, from larvae 

 that had evidently hibernated, and it is very probable that the Army 

 Worm Moths issue at about the same time. These may be known 

 as the first brood of moths of the season. The Army Worms which 

 I found in the Hungarian field were no doubt hatched from eggs 

 deposited in the month of June by the above moths ; and these 

 worms, after completing their transformations, would produce the 

 second brood of moths early in August. 



From the eggs deposited by this second brood of moths would be 

 produced the worms which I found in the latter part of August and 

 fore part of September; and these worms, after completing their 

 transformations, would produce the third and last brood of moths. 



The eggs from the third brood of moths would produce the hiber- 

 nating worms, and thus the cycle is completed. 



From this we see that there are three broods of these insects 

 produced in one season, and "that they hibernate in the larva state. 

 These observations apply solely to this locality of McHenry county, one 

 of the most northern counties of the State of Illinois. It is very 

 probable that in more southern latitudes one or more additional 

 broods are reared in one season. They also apply to the sedentary 

 race, or those which live throughout their entire lives as cut-worms. 



That there are two distinct races of Army Worms I have not the 

 slightest doubt. One of these has for many generations lived as 

 cut-worms, never migrating from one field to another, while the 

 other race at a certain season of the year migrate from one field to 

 another in large armies, and this race has manifested this migrat- 

 ing habit for many generations past. Of course this latter race 

 when young live as cut-worms until they acquire a certain size, 

 when they commence their migrations ; but the sedentary race, it is 

 my opinion, 7iever perform these migrations. 



This, it is true, is all speculation, as I have never had an oppor- 

 tunity of studying up the habits, etc., of the migrating Army Worms. 

 In making these remarks I desire to call the attention of those who 

 have an opportunity of studying both races of this insect to this 

 subject. 



