10. BULLETIN 966, U. S. DEPARTMENT OF AGRICULTURE. 
feeding on the leaves, when abundant attack the stalks, and attain 
full growth in about 3 weeks. They then transform to pups, and 
about 3 weeks later produce another brood of moths, making an 
approximate life cycle of 7 or 8 weeks, depending on temperature. 
At least two generations a year are produced in Virginia. 
This webworm may be controlled by arsenicals and by hand-picking 
on horse-radish and, more readily on other crops, by fall and spring 
plowing and frequent cultivation. 
LITERATURE CITED. 
(1) HuEBNER, Jacob. 
1792. SAMMLUNG AUSERLESENER VOGEL UND SCHMETTERLINGE. Augsburg. 
Pl. 82. (Not seen.) 
(2) WALKER, FRANCIS. 
1859. LIST OF THE SPECIMENS OF LEPIDOPTEROUS INSECTS IN THE COLLEC- 
TION OF THE BRITISH MUSEUM, Part XVIII. Pyralides. 1036 p. 
London. 
(3) Harris, T. W. 
1869. ENTOMOLOGICAL CORRESPONDENCE, EDITED BY S. H. SCUDDER. 3875 P., 
46 fig., 4 pl. Boston. 
(4) BucKLER, W. 
1882. NATURAL HISTORY OF PIONEA STRAMENTALIS. Jn Ent. Monthly Mag., 
v. 19, p. 126-130. 
(5) Meyrick, E. 
1895. A HANDBOOK OF BRITISH LEPIDOPTERA. 843 p., figs. London, New 
York. 
(6) FLETCHER, James. 
1905. REPORT OF THE ENTOMOLOGIST AND BOTANIST. Jn Ann. Rept. Exper- 
imental Farms for 1904. Can. Dept. Agr., p. 205-256, 2 pl. 
(7) CHITTENDEN, F. H., and Marsu, H. O. 
1912. THE IMPORTED CABBAGE WEBWORM. U.S. Dept. Agr., Bur. Ent. Bul. 
109, pt. 3, p. 23-45, fig. 4-7. 
(S) MarsuH, H. O. 
1918. THE HORSE-RADISH WEBWOoRM. U. S. Dept. Agr., Bur. Ent. Bul. 
109, pt. 7, p. 71-76, fig. 25-28. 
(9) CHITTENDEN, I’. H., and HowArp, Neale F. 
1917. THE HORSE-RADISH FLEA-BEETLE: ITS LIFE HISTORY AND DISTRIBU- 
TION. U.S. Dept. Agr. Bul. 535. 16 p., 6 fig. 
(10) Marsn, H. O. 
1917. LIFE HISTORY OF PLUTELLA MACULIPENNIS, THE DIAMOND-BACK MOTH. 
In Jour. Agr. Research, v. 10, no. 1, p. 1-9, 2 pl. 
(11) Crossy, C. R., and LEONARD, M. D. 
1918. MANUAL OF VEGETABLE-GARDEN INSECTS. 391 p., 232 fig. New 
York. 
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