THE BOUGH-HEADED COEN STALK-BEETLE 5 



September. The new generation of beetles do not appear to be 

 very active, remaining usually where they emerge, though they have 

 been found soon after emergence feeding upon the culms of Juncus 

 ejfusus and certain grasses of the genus Paspalum. 



EGG 



DESCRIPTION 



The egg when first laid is oblong, pure white, and perfectly smooth 

 (PL II, B). Subsequently the egg enlarges until it is nearly double 

 its original size and changes its form until almost globular (PL 

 II, B, C, D, and E) . Eggs measured by the senior writer averaged 

 about 2 millimeters in length and 1.5 millimeters in diameter. 

 These were several days old and approximately full size. No meas- 

 urements of freshly deposited eggs were made. 



METHODS OF COLLECTING AND INCUBATING 



A small number of the eggs used in the investigations were gath- 

 ered in the field, but the greater number were obtained from the 

 breeding cages. 



In the field the eggs were found in the ground, where it was usually 

 possible to obtain them by digging. 



To obtain eggs which were known with certainty to belong to the 

 present species, adult beetles were confined in suitable breeding cages, 

 from which the eggs were gathered at regular intervals. Each cage 

 consisted of a 12-inch standard-size flowerpot filled with finely-sifted 

 soil and covered with a cylindrical wire-screen top ; the whole outfit 

 had essentially the same form and arrangement as that portrayed 

 by Davis (5, pi. S, fig. 4). The soil in these cages was kept mod- 

 erately moist, and at« intervals, varying from a few days to a week 

 and a half, was passed through a fine-mesh sieve. The meshes in 

 this were fine enough to retain the eggs, which were then transferred 

 to the incubating boxes. 



In the breeding cages the beetles were first fed by transplanting 

 young corn plants to the cages, but as the labor of replacing the 

 food plants every few days proved burdensome, a handful or so of 

 corn kernels was buried in the soil. These proved to be a highly 

 satisfactory substitute, the beetles feeding upon them as readily as 

 upon the living plant. 



The receptacles used in incubating the eggs were rectangular tin 

 boxes like those used by Davis for the same purpose (5, pi. 4, fig- 7) • 

 These boxes were about three-fourths filled with finely-sifted earth, 

 which was kept to the right degree of moisture by occasionally add- 

 ing a few drops of water with a pipette. As the eggs were trans- 

 ferred to a box each was placed in a small pit made with the blunt 

 end of a pencil, and as the boxes were filled the lid was replaced 

 and they were then kept in the shade. Usually the lid would so 

 conserve the moisture originally in the soil that in most instances 

 it was unnecessary to add more water during the period of incuba- 

 tion. 



PLACE OK DEPOSITION 



The eggs are deposited in the ground, and apparently the females 

 exercise no particular care in the choice of a place in which to 



