2- BULLETIN 966, U. S. DEPARTMENT OF AGRICULTURE. 



Two other webworms affect horse-radish in the United States, both 

 introduced from abroad, namely, the imported cabbage webworm 

 (7)^ and the diamond-back moth (10).^ 



DESCRIPTION. 



THE MOTH. 



The moth of this species is rather bright ocher yelloAv and the 

 forewings are traversed by two irregular lines dividing the wing into 



thirds of ne a r 1 y equal 

 width. Near the tip of the 

 forewing is a conspicuous 

 lighter spot and another 

 larger rounded one near 

 the middle of the anterior 

 border. Directly outward 

 from this latter there is an 

 angular 8-shaped spot. 

 The wing expanse is about 

 1 inch (25 mm.) and the 

 length of the body a little 

 less than half an inch (10 

 mm.). This moth resem- 

 bles in general contour the 

 related E. rimosalis Guen., 

 but may be readily distin- 

 guished by the characters 

 given and with the aid of 

 the accompanying illustra- 

 tion (fig. 1). In some in- 

 dividuals the outer edge of 

 the forewing is much 

 darker than in others, 

 darker even than in E. 

 rlniosalis. 

 The following more technical description is after Meyrick (5, p. 



Fig. 1. — European horse-radish webworin (Everyestits 

 stramiiialis) : a. Moth, normal form ; h, moth, 

 dark form. Twice natural size. 



m 



): 



Fore- wings pale oclierous-yellow, sprinkled with darlv brown, veins pos- 

 teriorly dark brown ; lines dark fuscous, first angulated above middle, angu- 

 larly indented above angle, second unevenly curved ; an angularly 8-shaped 

 discal spot, outlined with dark fu.scous, touching angle of first line; a cloudy 

 dark fuscous subterminal line, forming above middle a strong dark sulTusion 

 inclosing a pale terminal spot. Hindwings prismatic yellow-whitish ; traces 

 of a dark posterior line ; termen narrowly, dark fuscous. 



' Hellula undalis Fab. 



^ Plutella maculipennis Curt. 



