May, 1914.] 
Egg-Laying of the Rice Weevil. 
321 
EGG-LAYING OF THE RICE WEEVIL, CALANDRA 
ORYZAE LINN. 
Frank H. Lathrop. 
The Rice Weevil, Calandra oryzce Linn., is well known through¬ 
out the United States as a stored grain pest. It is especially de¬ 
structive in the South, however, where it is known chiefly because 
of its injury to com (1, 4). In fact, it is often locally called 
the Corn Weevil. 
While studying the pest, the writer was impressed by its high¬ 
ly adaptive method of oviposition, and the belief that a study 
of the habit would be interesting and of some economic impor¬ 
tance led to the observations included in this paper. 
The work was performed at Clemson College, South Carolina, 
during the winter of 1912-1913, under the direction of Professor 
A. F. Conradi, State Entomologist, to whom the writer is indebted 
for valuable suggestions and assistance. The cuts are used through 
courtesy of the South Carolina Experiment Station. 
WHERE THE EGGS ARE DEPOSITED. 
Each egg is deposited singly in a cavity previously dug in the 
grain by the female beetle. Preparatory to oviposition, the 
weevil moves over the surface of the com several times, examining 
it thoroughly by means of the tip of the proboscis and the antennae 
before a .suitable place is decided upon. When the place has finally 
been chosen, the excavation of the cavity is immediately begun by 
gnawing the material with the mandibles. Unless disturbed, the 
weevil will usually finish the cavity when once started, but its 
completion is by no means certain, for the weevil often becomes 
apparently dissatisfied with the location even after the cavity is 
well started, and a new location is sought. 
The place selected is usually near the edge of the com, and, 
when in position to excavate, the weevil is almost invariably 
straddling the edge of the kernel. Nearly all of the eggs observed 
were deposited in the soft starch or in the germ. Only rarely 
was one placed in the homy starch, while a favorite location was 
at the junction of the germ with the soft starch, and also at the 
junction of the soft starch with the horny starch. 
In order to facilitate observation, the weevils were provided 
with grains of corn that had previously been cut in two longi¬ 
tudinally. The eggs were deposited on the broken surfaces of 
these half-grains, except in a few cases where they were deposited 
in the genu at the point where it had been attached to the cob. 
The outer, homy surface of dry corn is apparently too hard for 
the weevils to penetrate, for no eggs were observed in this region, 
and, even when only whole grains were provided, the eggs were 
deposited either in the genu or in the soft starch at the outer end 
of the kernel. 
