APPENDIX I REPORTS OF OBSERVERS. 377 



HELIOTHIS. 



NATURAL HISTORY. 



Unlike the cotton caterpillar, the boll-worm is not confined to one species of plant 

 for its food, but is omnivorous, feeding for the most part on living vegetable substances, 

 but occasionally becoming carnivorous when partly grown. From this it results that 

 its eggs are not deposited exclusively on one species of plant; nor, when laid on the 

 cotton-plant, are they confined chiefly to one part of it, as was found to be the case 

 with those of Aletia. On the contrary, I have found them laid singly ou the outside 

 of the calyx and on the leaf petioles of the garden pea, on the peduncles and leaves 

 of the cow-pea, on the upper surface of leaves of Indian corn, near their divergence 

 from the stem, and on the outer surface of the husk near the tips of young roasting- 

 ears, and on the petioles and both surfaces of the leaves of the cotton-plant, as well 

 as on the outer surface of the bracts composing the involucre which surrounds the 

 flowers of this species, and which, is known to farmers as the square. Not having 

 allowed moths of this species to lay in confinement, nor having marked any eggs im- 

 mediately after their disposition on cotton in the field, I cannot say how long a time 

 is required for incubation. 



Very soon after its exclusion the young larva begins to feed upon the substance of 

 the leaf or bract, or other organ on 'which it finds itself, and when this chances to be 

 a leaf or bract it leaves the epidermis on the other side for some time. During the 

 first half day or day of its existence it feeds in this way, forming small, irregular, 

 transparent spots in the blade of the leaf or in the bract, after which it pierces a 

 hole usually more rounded than that first formed by Aletia through the organ. The 

 age at which this is done appears from my observations to be earlier than that at which 

 the cotton caterpillar pierces the leaf, but I find that it differs greatly with different 

 individuals, some piercing the leaf when less than ten hours old, some not until they 

 are about tAvo days old. After this, if it does not find itself close to a flower-bud, im- 

 mature fruit, or some other object suitable for its food, the larva moves about in search 

 of this food, finding which it shortly goes to eating. Whatever may be its food, this 

 worm, according to my observations, always forms regular, round openings in its ex- 

 terior for its own entrance or exit, and these vary in size with the size of the larva, 

 being just large enough to allow the animal's body to pass with ease. Another pecu- 

 liarity of this larva is its wandering character, especially earlier in the season, when 

 feeding on the flower buds or forms of cotton, for, these being small, the contents of 

 each is soon eaten by the worm, which necessarily moves on in search of more food. 



My attention having been given more to Aletia than to this species, especially in 

 the early part of the season, I find that the notes from which I am to judge of the 

 number of broods of the boll-worm are very incomplete. But from such notes as I 

 have it appears that there were four broods, of which only the last did much injury 

 to cotton, most of the earlier broods feeding upon the Indian corn. 



When, about the middle of May, I began studying this insect, I found what I sup- 

 pose to have been its first brood of larvae feeding upon the tender leaves which termi- 

 nate the young stalks of maize ; it is then sometimes called the " terminal-bud worm " 

 of the corn. It is rarely that more than one larva is found on any plant. Plants 

 attacked by these bud-worms are easily singled out as one walks through the field ; 

 for the leaves are pierced by many small holes, much as though a light charge of bird- 

 shot had been fired through the plant. When such a stalk is found, if the leaves, be- 

 ginning with the outermost, are carefully stripped off nearly to the bases of their 

 sheaths, a quantity of excrement will be found between them, increasing as we go in- 

 ward ; and the pale green larva which causes it will be found either within the sheath 

 of a leaf or in a cavity that it has eaten in the closely-rolled terminal leaves, which, 

 sooner or later, it always reaches. When it has attained its full size, the larva pierces 

 the leaves about it with a round hole, through which it makes its exit, going into the 

 ground for pupation. It is my belief that this brood went into the ground late in 

 May, being followed by another brood which pupated about the end of June ; but this 

 is in great part based on memory. 



Early in July, when roasting-ears were forming on the corn, another brood, the so- 

 called ear-worm or tassel-worm, was found feeding upon the silk and tender grain 

 near the end of the ears. While for the most part the preceding broods varied little 

 in color, being chiefly of a pale green, this brood consisted of larvae of various shades 

 of green, pink, and rose. When fully grown which occurred in the latter part of 

 July each of these bored a round hole through the husk of the ear, escaping through 

 this and falling to the ground to pupate. 



The next brood, appearing not far from the 1st of August, when the ears of corn 

 were beginning to harden and when cotton forms and bolls were very plentiful, was 

 chiefly confined to the latter. Before this time, a few larvae of this species had been 

 found on cotton ; thus, on May 30, 1 found a partly grown boll- worm eating the leaves of 

 a cotton-plant ten or fifteen rods from any corn, and at this time there were very few 



