[18] 



aud of the silka aud grains of the growing ears. The presence of the worm on yonng 

 corn plants is indicated by round holes cut in the blades, and the worm and its excre- 

 ment may usually be found in the sheath. There is generally no external evidence 

 of the w^orm on the ear ; it eats the silk and tender grains at the distal end, and as it 

 consumes the juicy grains it lies in the cavity thereby made, the excremeut remain- 

 ing behind it and between the husk and cob. In order to find the corn worm (Helio- 

 ihis armigera) on the ear, it is, therefore, necessary to open the husk. I have found 

 the worm grows more rapidly when it feeds on corn grains than on any other food, 

 though the size of the worm at maturity is no larger, and I could not discover that 

 the moth raised from the corn worm differed from other Heliothis moths more than 

 those raised on cotton differed from each other. After these general remarks I will 

 give the history of Heliothis as it was developed by my studies. It is proper to re- 

 mark that my systematic work began about the middle of July, and even then my 

 attention was for some time mainly directed to the preparation of vegetable extracts, 

 infusions, and decoctions, in the hope of finding some plant or plants indigenous to 

 this locality that possessed insecticide and insectifuge properties. 



The egg. — It was very difficult to find the'eggs. I never found, with the most care- 

 ful search, more than two or three on a plant ; sometimes not an egg on a plant. 



The egg is white, clear white, with sometimes a yellowish or brownish coloration 

 at the apex. It is fastened to the part of the plant on which it is deposited, very- 

 much as the egg of Aletia, by a gum. It is a little larger than the egg of the Cotton 

 Worm Moth (Aletia), and sculptured very much in the same way. 



I found them on the involucre of the flower or young boll, on the pedicel or flower 

 stem, near the torus or receptacle, on leaves and on petioles or leaf stems. In the hot 

 vreather of July and August, the larger number of eggs was found on the under side 

 of the thickest, darkest leaves. The duration of the egg state is from three to five 

 days. 



The larva. — The larva hatches and at first feeds on the tender parenchyma of in- 

 volucre or leaf, and makes its way as quickly as possible to a flower or young boll. 



In July and August the large majority of young Heliothis larvae were found within 

 the corolla, eating sometimes the essential elements of the flower and sometimes the 

 petals. They seemed to he specially fond of these floral parts. While on the buds of 

 flowers feeding they were quiet, but if seen on the leaf or stem they exhihited signs 

 of restlessness and moved from point to point. Every flower bud and every flower 

 attacked by them fails to produce fruit. The worm, when small, moves with great 

 ease and with comparative rapidity, ''looping" as it goes. As it grows larger its 

 movements are less easy, and it is more liable, when disturbed, to fall from the plant. 

 When a few days old, if bolls are oh the cotton, it attacks these, seeming at first to 

 prefer the small, tender bolls and afterwards the large ones. It bites off the outside 

 slick, hard covering sufficient for a hole, allowing the entrance of the worm, and 

 thereafter it feeds on the juices and seeds and cotton in the interior of the boll. Some- 

 times it cuts oft" a part of the outside of the holl in one, two, or three places without 

 entering the interior, but this always insures the falling or rotting of the boil ; the 

 bite of the worm seems to be poisonous to buds, flowers, and bolls. The hole in the 

 boll is often made between the holl and the calyx, so that the worm is concealed 

 while at the work of x) erf oration, though this is not always the case. 



If a worm feed on a large boll and the excrement on the boll be exposed to rains, 

 the coloring matter will be washed away and the fibers of cotton can be seen dis- 

 tinctly. I observed this for the first time on September 14 : during the few days 

 following before the disappearance of Heliothis, I saw numerous instances of it. The 

 cellulose was unchanged by passing through the worm. In September I saw Helio- 

 this feeding on cotton leaf in a field of cotton in which Aletia was abundant and 

 where whole leaves were very rare ; a good proportion of bolls was yet unopened. 



I observed Heliothis on corn and on cotton at the same time and in different parts 

 of the same field. The number of Heliothis did not seem to increase on cotton after 

 the corn was matured. 



Boll Worms eat each other. I have seen the statement that if two or more Boll 

 Worms are started in a single package, even with a full supply of appropriate food, 

 only one reaches the destination, and that if more than one larva is confined in a 

 breeding cage one invariably devours the others. The latter statement I am prepared 

 to contradict; repeatedly during the summer I had as many as three moths to issue 

 about the same time in the same jar. 



Boll Worms eat the chrysalids of Cotton Worms. I have seen them in the act, but 

 I have never seen the larva of Heliothis eating the larva of Aletia. 



The color of the Boll Worm varies greatly ; when young it is slender and green, hav- 

 ing a number of yellow and white bands and lines running longitudinally from the 

 back of the head to the anal extremity ; rarely these larvse retain the green color 

 throughout the larva state, but generally the color changes, as the worm grows, to 

 yellowish or brown, the longitudinal lines and bands remaining; each segment of the 

 body bears eight black spots, from each of which projects a stiff bristle. On the seg- 



