126 FIEST ANNUAL REPORT OF THE STATE ENTOMOLOGIST. 



Attracting to tight. — Another method of collecting the moths is to 

 atti'iict them to lamps so constructed that the insects flying to them 

 shall fall into a reservoir arranged for the purpose, where they "svill be 

 destroyed, as illustrated in Fig. 38 on jiage . Many styles of lamps 

 liave been devised which have been experimented with by the U. S. 

 Entomological Commission in the cotton-fields of the South, and illus- 

 trated and explained in the Annual Reports of the Commission. The 

 simplest form is that which is constructed as a torch, the oil reservoir 

 being soldered to the center of a broad tin dish containing water with 

 a small quantity of kerosene oil floating upon it, and fastened on the 

 top of a stake thrust in the ground. 



Benefit of Destroying the First Brood. 



To illustrate the great importance of destroying the insects which 

 would produce the first brood of a many brooded species, and the ease 

 with which subsequent multiplication may at this time be prevented, 

 we present the following calculation, showing the results which would 

 follow the above experiments conducted /o?' a single niglit, upon the 

 supposition that each female of five successive broods* would have de- 

 posited its full quota of eggs, and that each Q^g would have produced 

 a moth. It is scarcely necessary to add that not even a near ai)proach 

 to such an entire exemption from loss in the four distinct stages of in- 

 sect life can ever occur in nature. 



The average number of moths to a plate, as given above, being twenty- 

 six, the entire number captured during the niglit would have been 

 four hundred and sixty-eight. Assuming one-half of these to have been 

 females, and each to contain five hundred eggs,f the caterpillars of the 

 first brood would number one hundred and seventeen thousand. By the 

 same method of calculation, we have for the second brood, twenty-nine 

 and a quarter millions of caterpillars ; and continuing the computation 

 until we reach the fifth and last brood, Ave have the amazing number 

 of 457,031,250,000,000 caterpillars, or exceeding four hundred and 

 fifty-seven trillions. 



To present this computation in a more convenient and comprehen- 

 sible form, — under the above conditions and by the same progressive in- 

 crease, a corn-moth emerging from its pupa in May would be repre- 

 sented by a progeny of nearly two trillions of caterpillars (1,953,125,- 

 000,000) in its last annual brood in November, — a number fourteen 

 hundred times greater than that of the entire human population (as 

 estimated) of the globe. 



*In all but the extreme southern portion of the cotton-belt, there are, normally, five an- 

 nual broods — the last appearing early in September. In exceptionally fine seasons, it is 

 probable that there is also a sixth brood. {Rept. Commis. Agricul., for the year 1879, p. 

 842.) 



+A boll-worm moth, dissected by Dr. Jno. Gamble, contained upwards of five hundred 

 eggs (Glover— Rept. Commis. Pat. {Agricul.), for 1855, p. 282). 



