346 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



migrate to corn or cotton ; but, inasmuch as corn appears to be its favorite 

 food, its numbers could be very greatly lessened, and its injuries to cotton 

 could be almost done away with by this i>rocess. We advise planters 

 by all means to try.it, and we assure, them that their time will not be 

 lost. In sections of the cotton-belt which are badly troubled with the 

 boll- worm, and where corn is not grown, it will be well to plant the latter 

 crop and use it as a trap, as advised above. 



Rotation of crops. — In the light of the relation of the corn and boll 

 worms, and of the numerous food-plants of HeliofMs, we may here men- 

 tion the fact that rotation of crops has been strongly urged as a pre- 

 ventive against the ravages of the boll-worm. The knowledge which 

 we have gained of the multivorous habits of the insect readily shows us 

 that such a course would be vain, as during the season when cotton was 

 not grown some other food-plant would be available. As a curiosity, we 

 may mention the fact that some years ago a writer in the Southern Cul- 

 tivator, after earnestly urging rotation of crops, advises corn as the best 

 crop to rotate ivith cotton ! 



Destruction of the CHRYSALroES. — In the more southern portions 

 of the cotton-belt, where the frosts are rarely severe, but little can be 

 done toward the destruction of the chrj'salides beyond instructing the 

 plow-hands to crush them whenever they observe them in i)lowing, or 

 causing a boy to follow the plow and collect them as they are brought 

 to the surface. In the more northern i)ortions, however, /ttZZ^ZoicMigr 

 may accomplish much good. Exijeriments, having the testing of the 

 efficacy of this remedy in view, have been made by Professor French. 

 We can do no better than to give his own words : 



Fall plowing. — To make it plain how this is to reach them, I shall have to explain 

 Bome ohsen^ations made on tho fall brood of chrysalides that -were found during tho 

 month of NoveniLer in a field where the worms had been very abundant in the com 

 before it was harvested. In digging for the chrysalides round^ the corn-hills, I found 

 that instead of their occupying an oval eartbem cocoon, as has usually been written 

 of them, and as they apparently do in the bieeding-box, they were down in the ground, 

 from live to six inches below the surface, in a hole about a third of an inch in diameter, 

 reaching from tho chryGalis to tho toj) of the ground, where it was covered over with 

 a thin film of dirt Ixoin an eighth to a quarter of an inch thick. This hole was larger 

 at the bottoni than at tlie top, apparently, so as to give fiee motion to the chrysalis, 

 and usually bent in its course so that the lower part would have an inclination of 

 perhaps forty-five degrees. At the bottom would be found the chrysalis, the small 

 end downward and the head upward. 



In one case I found the hole so bent that the chrysalis occupied a horizontal position. 

 The hole was smooth inaide, and was perliaps made so by cementing the dirt together; 

 but of that I could not tell, for the wiiole ground was moist, though dry enough to be 

 firm. I took several of the chrysalides and \n\t them in a box with some loose dirt, 

 and then moistened it, after whicli I allowed them to freeze. The dirt, when they 

 were .allowed to freeze, was dry enough, so that if it had been in the garden and turned 

 over with a s])aiie it would crumble. When examined, after the freezing, all were 

 dead. Some others, taken up in the bottom of their subterranean habitations, with- 

 out sifting the looso earth round them in their holes, and allowed to freeze, were not 

 kUled by freezing. 



My concliTsious were, that so long as they were in the smooth compartments they 

 had made for themselves, free from any loose dirt that would become wet and stick to 

 them, they could pass the v/inter in safety, even though they might be frozen ; but, 

 when the dirt was packed loosely round thorn and became wet and stuck to them, 

 then freezing killed them. Their holes, running cell-like as they do from the surface 

 down into the ground five or six inches, must be broken up by plowing, and when 

 once broken up with the loose dirt round them the rains and the freezing winter 

 weatber would have the same effect on the chrysalides that moisture and freezing had 

 on those in tlie box of loose dirt. F.all plowing, then, for these reasons, will probably 

 be the moat efficient means of destroying these insects; besides, if done late enough, 

 it will rid the ground of cut-worms, &-C. 



Destrttotion of tee MOTHS.-r-It is the general opinion throughout 

 the South that the best if not the only way of getting rid of the boll- 



