Journal of Agricultural Research voi. x. no. i 



THE LARVA 



The newly hatched lan^a is a minute, light-colored creature with a dark 

 head. The mature larva (PI. i, S) is about three-tenths of an inch in 

 length, slender, fusiform in shape, and dull green in color. The head is 

 light colored and marked with brownish spots or lines. 



In habit the larva is irritable, and, when disturbed, wriggles about 

 actively. When feeding on tender-leaved plants (PI. i , Z>) , the larva cuts 

 entirely through the leaf, but with plants like cabbage, having thick 

 leaves, it removes irregular areas of the lower surface without cutting 

 through the upper epidermis. During cool weather the larvae burrow 

 into the leaves immediately after hatching, and for the following two to 

 four days live in irregular blotch mines, which they form between the 

 upper and lower epidermis. 



THE PUPA 



The pupa (PI. i , C) is slender, yellowish or whitish in color, and often 

 striped with brown. It is about one-fourth of an inch in length and is 

 inclosed in a beautiful, delicate, lacelike cocoon of white or grayish silken 

 threads, attached to the leaves of the food plant, often along the midrib. 

 In cool weather larvae occasionally pupate in cracks in the soil about the 

 base of the host plant. 



DISTRIBUTION OF THE MOTH 



The diamond-back moth is a cosmopoUtan species which in the United 

 States apparently occurs wherever cabbage {Brassica oleracea capitafa) 

 is grown. 



In September and October, 1908, the several stages were noted by the 

 writer on cabbage and turnip (Brassica rapa) at Santa Ana, Orange, 

 Tustin, Garden Grove, Whittier, and Watts, Cal. From January to 

 June, 1909, the larvae were noted on cruciferous vegetables at Browns- 

 ville, Tex., and other localities in the lower Rio Grande Valley. In July 

 and August, 1909, larvae were noted on cabbage at Houston, Dallas, and 

 Amarillo, Tex., and at Rocky Ford and Greeley, Colo. In December, 

 1909, and January, 1910, larvae were found on cabbage and turnip at 

 Lake Charles and Lake Arthur, La., and at Beaumont, Corpus Christi, 

 San Antonio, Sabinal, and Laredo, Tex. From July, 1910, until Feb- 

 ruary, 191 1, larvae were frequently found on cabbage, turnip, and water- 

 cress (Radicula sinuata) at Honolulu and Wahiawa, Oahu, Hawaiian 

 Islands. At Honolulu the species was kept under fairly close observa- 

 tion, and it was noted that the larvae did not become sufficiently numer- 

 ous at any time to cause appreciable damage. During February and 

 March, 191 3, larvae were noted on cabbage at Thermal, Coachella, Calexi- 

 co, and El Centro, Cal. In May and June, 1913, larvae were found on 

 cabbage at Marion, N. C, and at Chester, N. J. All stages of this insect 

 were found on various cruciferous plants at Phoenix, Glendale, Tempe, 

 and other points in the Salt River Valley of Arizona during January and 



