THE HAWAIIAN BEET WEBWORM. 3 



LIFE HISTORY AND HABITS. 



All stages of this pest can be found throughout the year. The moths 

 (fig. 1) are usually to be found in abundance among the foliage of 

 Amaranthus, beets, or other low-growing plants. During the day they 

 remain concealed, usually on the underside of the leaves, but when dis- 

 turbed they fly readily. They are but rarely attracted by lights. The 

 scale-like iridescent eggs (fig. 2, a) are almost invariably deposited 

 on the underside of the leaves. They are placed singly, in pairs, 

 or in rows of five or more. On beet leaves, the favorite place for 

 depositing eggs is along the midrib and larger veins. As many as 

 40 eggs, which had been deposited in the field under normal condi- 

 tions, were counted on a single beet leaf. The eggs have been ob- 



Fig. 1. — The Hawaiian beet webworn (Hymenia fascialis) ; Female moth. Enlarged. 



(Original.) 



served to hatch in 4 days. The young larvae feed on the lower sur- 

 face of the leaves. On beets, and probably on other plants, the 

 larvae, except when nearly mature, consume only this surface. This 

 habit of remaining on the underside of the leaves, without eating 

 through the upper epidermis, adds to the difficulty of successfully 

 treating this pest with insecticides. (See larva and details, fig. 2, 

 b-e.) 



In some cases the larvae spin light webs, under which they rest. 

 This web- forming habit is not very pronounced, and it is not unusual 

 to find hundreds of larvae without any webs whatever. 



Under normal conditions the larvae reach maturity in from 9 to 

 13 days. They then leave the plants, burrow slightly beneath the 

 surface, and form firm, compact, oblong cocoons of webbed-together 



