THE CLOVER ROOT BORER 33 
firstandin approximately the same direction from it, but with a small 
wooded area between, showed at the same time no serious damage. 
These observations may be explained by the fact that the greater 
number of root borers appear to fly below a height of 30 feet, and 
thus the wooded country encountered acts as a barrier and causes 
them to gather in indentations on the edges of the woods, or turns 
them back into the clover fields on the windward side. This assump- 
tion is borne out by accumulated flight records and records of 
collections of beetles taken in flight along the windward margin of 
woodland areas. Advantage might be taken of this barrier effect to 
ward off root borer injury;in farming communities that are isolated by 
surrounding woodlands from other farming communities. 
OTHER HOST PLANTS 
Common red clover, Trifolium pratense, and mammoth clover, T. 
medium, are the preferred host plants of the clover root borer. Alsike 
clover is attacked and may be severely injured, especially in sections 
where recent changes have been made from red clover to alsike in the 
general cropping practice. The roots of alsike do not appear so well 
adapted as a nidus for the root borer as are those of red clover, prob- 
ably because of their more sappy, tender texture. That alsike is not 
an altogether suitable host is indicated by the fact that adults which 
had been killed by a fungus before penetrating very far in alsike roots 
were commonly observed at Forest Grove in 1921. 
Clover root borer adults have been observed attacking alfalfa and 
sweet clover plants in the Yakima Valley, Wash. They were found, 
two or three to a root, in superficial burrows in the crowns of these 
plants, which were growing in an orchard where the clover had been 
practically all killed by the root borers. Adults were found dead of 
fungous disease in such superficial burrows on sweet clover crowns. 
These observations were made on May 22; on a later visit, C. W. 
Creel was unable to find living root borers in any stage on these 
lants. The indications in this case were that the root borers had 
een forced by hunger to attack alfalfa and sweet clover roots, find- 
ing no other food in the immediate vicinity, and had not been success- 
ful in reproducing on these plants. The roots in this case were of 
large size. It is possible that the borers might have been more 
successful on younger, smaller plants, as Gibson (13) stated that in 
Ontario ‘‘In some fields of alfalfa this borer was working freely, caus- 
ing noticeable loss. In one field examined 31st July, two adult bee- 
tles were found in a root which had been tunneled by the larve.”’ 
Folsom (12, p. 114) also stated that the root borer feeds on alfalfa, 
‘but not enough to have done any damage up to the present time.”’ 
Schmitt (39, p. 392-393) stated that he did not observe clover 
root borers on Medicago sativa and Hedysarum onobrychis (Onobrychis 
visiaefolia) near Mainz. Kaltenbach (25, p. 121) included Medicago 
satwa among the plants whose roots are attacked by this species, and 
Vassiliev (43) listed this insect as a pest of lucerne in Russia. Del 
Guercio (16, p. 264) stated that alfalfa is not known to have been 
attacked by it in Tuscany.’ 
There is a large acreage of alfalfa in the Yakima Valley, Wash., in 
the vicinity of clover fields severely infested by root borers, but no 
- evidence of infestation by root borers has yet been found in these 
