22 I'BfiLlMli^AEY EEPOEt OK ALFALFA WFEVIL. 
larvge, as observed by him, were remarkably vigorous, very young 
ones exhibiting great energ}^ as travelers. Their mode of progression 
is to reach forward and then, with a shght hump, to bring up the rear 
part of the body. The head is at once thrust forward again. About 
one move is made per second, and three propulsions will carry the body 
forward 1 mm. When in doubt as to the direction to be taken, the 
larva elevates the head and swings it from side to side until some 
decision is reached, when the journey is resumed. The larvse are 
positively phototropic. 
After working their way upward on the alfalfa stems the larvae 
begin to feed close down between the opening buds on the unfolding 
leaves. Their manner of feeding there, as observed by Mr. Ainslie, 
was by scraping off the epidermis with a sort of burrowing motion, 
leaving only the veins and fragments of uneaten tissue. This selec- 
tion of the terminal buds may be in part due to the shelter offered 
as well as to the more tender and succulent nature of the plant 
growth. Large numbers of young larvae may, however, be found 
feeding among the unfolding buds without being easily seen. This 
feeding is further described by Mr. Titus ^ as follows : 
In feeding, the larvae bore holes into the buds [see fig. 4], working their way in 
until they are often completely concealed inside the opening bud. The plant then 
sends out other buds below this point, and usually other young lar^'se are present to 
destroy these, so that at times the growing tips of the plants become so injured as co 
give these tips the appearance of a gall. As many as 15 young larvae have been found 
feeding in the terminal bud of one stalk. Sometimes, before they are fully developed, 
in the second stage, they pass out onto the leaves, at first eating the upper epidermis 
only. 
The lai'vae, after the usual habit of those of the genus to which it 
belongs, either cling around the edge of the leaf or feed in a curved 
position. This continual eating off of the fresh growth keeps the 
alfalfa so reduced that it does not produce a first crop. Seriously 
affected fields are shown in Plate III, figure 1, and Plate IV, figures 
1 and 2, while a field that has not suffered from such attack is shown 
in. Plate IV, figure 3. From these illustrations a good idea of the 
damage done by the larvse to the first crop of alfalfa may be obtained. 
LARVAL PERIOD. 
From about 5 to 8 days after hatching from the egg the skin of 
the larva splits and the old skin is pushed off, leaving the larva in a 
new dress. This process is repeated after a period of from 12 to 20 
days and again after about 12 to 30 days, as observed by Mr. Titus. 
Mr. Ainslie in some instances got pupae in 18 to 20 days during May, 
1910. These variations in time are probably largely due to tem- 
perature, which again may be due in part to elevation. 
1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp. 40-42, September, 1910. 
