THE 1921 OUTBREAK OF THE CLOVER-LEAF WEEVIL 
^ • IN IOWA 
H. L JAQUES 
Early in the spring of 1921 it became apparent that many 
clover meadows were suffering severely from some trouble. The 
entire stand was killed in an occasional field while in others 
patches throughout the fields were killed - or the plants were very 
much stunted. At first it was thought by many to be winter- 
killing but it was soon found to be insect injury due to the work 
of the Clover-leaf Weevil, Hypera punctata Fab., and one or more' 
species of cut worms. It was thought in some quarters that the 
matter was further complicated by the presence of a fungus 
disease of the roots. As far as the writer observed this root 
injury seems to have been an infection naturally following the 
insect damage. 
The clover-leaf weevil, which originally came from Europe, 
has been known in this country for a half century or longer. It 
can be found almost any season in almost any clover field but has 
never before been known to do such general and widespread 
damage within the state of Iowa as during the spring of 1921. 
The clover-leaf weevil has but one brood per year. The eggs 
are laid on various parts of the clover or alfalfa plant. A good 
percentage of the eggs hatch and reach the first, second or third 
instar as larvae before hibernating. The later eggs do not hatch 
until spring. The larvae are yellowish green or bluish green (a 
small percentage pinkish) with a white dorsal stripe and when 
fully grown measure from 1/3 inch to a little more than 1/2 inch 
in length. Cocoons with a unique golden brown silky network 
covering are formed -on or immediately under the ground, pupa- 
tion occuring in May or June. The adult, a brown snout beetle, 
begins to emerge in June and many continue to live until winter 
sets in or later. 
They were found feeding on the common red clover and on 
alfalfa although the injury to the clover was much the worse. 
The leaf blades and petioles and the more tender stems of the 
plants were eaten. In many cases the crowns of the plants were 
literally filled with the larvae. 
Counts of weevils were frequently made. It was not uncom- 
