114 REPORT UPON COTTON INSECTS. 



larval specimens with which they were accompanied, I have heen able to prepare the 

 following account : 



This insect appears to be but little known in science, although the injury to property 

 which it causes is perhaps greater and more deplorable than that occasioned by any 

 other with which we are acquainted. On the years of its appearance, the entire cotton 

 crop of certain districts is often cut short, and in not a few instances single plantations 

 have suifered to the amount of from ten to fifteen thousand dollars. 



It is one of the span-worms or Geometridae, belonging to the same family of insects 

 as the canker-worm, which is so much feared by horticulturists of the North. 



I have as yet only seen the larva. It is not indigenous to the Southern States, and 

 there is no evidence that it can live naturally north of the shores of Texas. Most 

 probably it is a native of Brazil or some other equatorial climate in that vicinity, for 

 it is so sensitive to the cold as to quickly die in an atmosphere, even approaching the 

 freezing point. It appears, then, on the Southern cotton fields always as in migration, 

 coming suddenly like a foreign enemy and always selecting the most thrifty planta- 

 tions. It is very remarkable, therefore, that it should appear regularly at intervals of 

 every three years in the same districts, striking first the seaboard and progressing 

 gradually inland as circumstances may favor. But equally remarkable in this connec- 

 tion is the fact that its most extensive and deplorable ravages occur always after inter- 

 vals of twenty-one years, or every seventh time of its advent, as shown in the years 

 1804, 1825, and 1846 during the last half century. These facts are inexplicable, unless 

 referable to some peculiar conditions of their economy in their native land. Little is 

 known from what southern direction they come, for, like all insects of this family 

 their movements are made at night, and the seaboard planter often rises in the morn- 

 ing to find whole sections of his plantations covered w ith the adult insects busily en- 

 gaged in depositing their eggs on the tender leaves of the cotton. There is, however, 

 no regularity in the exact month- of their coming, for Mr. Chisolm says that on his 

 plantations they came in 1840 quite early, but in 1843 much later, and remained until 

 frost ; in 1846, in June, and in 1849 and 1852 in August. 



The cotton-caterpillar is nearly always accompanied directly by another insect, 

 called the boll-worm (probably one of the Noctuidae), which confines its attacks to the 

 immature lint and seeds of the green pods of the short-stapled variety of cotton ; and, 

 as short cotton is mostly cultivated in sections farther south than those of the long- 

 stapled variety, this boll-worm is generally seen in Texas and Mississippi six weeks 

 or so before the cotton-caterpillar proper appears on the coast of Georgia and South 

 Carolina. Little is known of its habits more than this ; for its ravages are compara- 

 tively so inconsiderable that it attracts scarcely any attention of the planter. Its 

 concomitancy with the true cotton-worm, however, is not a little remarkable, and 

 there is no doubt that it belongs to a different family of insects. 



The cotton-insect having made its appearance, shows considerable sagacity in always 

 seeking first the most luxuriant fields. The eggs, which are of a dull white color, are 

 deposited singly, or at most in twos, on the under surface of the most tender leaves. 

 Their period of incubation is quite short, being six or seven days, and the time of 

 hatching is always after sunset or in the night. They then begin to feed ravenously, 

 and grow in proportion, their attacks being always confined to the long-stapled vari- 

 ety when accessible, though, when hard pnshed, they will eat the short variety ; but 

 never anything else ; and if their numbers are disproportionate in excess to the cot- 

 ton at hand, they will die of starvation rather than touch any other vegetable. 



During their caterpillar state they are almost wholly unaffected by all changes in 

 the weather, excepting cold; for the heaviest rains and the severest gales of wind do 

 not stay their movements or prevent in the least their devastations. Mr. Chisolm 

 says that a very violent hurricane of two or three hours' duration, which swept over 

 his plantations in August last, made no impression whatever on their progress. If, 

 however, there occurs even a slight frost they are killed throughout. These circum- 

 stances are worthy of mention, as bearing upon their probable tropical origin. Their 



