April, '15] 



McCONNELL: UNIQUE TYPE OF INSECT INJURY 



263 



on a slight elevation and permitting the beetles to pass the winter 

 above the general level of standing water in many places. 



The beetles emerge from hibernation early in the spring. At Green- 

 wood, Mississippi, this occurs about the first of April. On the Gulf 

 Coast this occurs considerably earlier, and in the extreme southern 

 part of this country they may not hibernate at all. On emergence 

 they begin to feed chiefly upon garden beans and also what native 

 food plants they can find. xAfter feeding for a week or more, oviposi- 

 tion begins. 



The eggs are placed in the ground within a few inches of the base 

 of the plants and at varjdng depths. In loose soil they may be found 

 within one-quarter of an inch of the surface, but the beetles frequently 

 place them on the under side of clods of earth, in crevices, and between 

 the base of the plant and the earth. They may in this way be placed 

 a couple of inches below the general surface. Occasionally they are 

 placed on the surface in damp shaded situations. Eggs have been 

 found in clusters of from 1 to 49, the average size of a cluster being 

 about 12. The eggs are of a deep yellow to orange color, elliptical, 

 reticulate, and about .70 mm. long by .35 mm. in diameter. A single 

 female has laid as many as 795 eggs, but the average is probably con- 

 siderably less than this. Oviposition continues over a period of 

 several weeks to a month. The eggs hatch in about 18 days in the 

 spring, while in summer this period may be shortened to a week. 



The larvae at hatching are about 1.5 mm. long and when full-grown 

 reach a length of 8-10 mm. At first they are of a creamy to a pale 

 orange color, and the egg shells also retain the orange color after 

 hatching. The larvae later become pure white. The head, cervical 

 shield, and anal shield are always black. 



They feed upon the roots, root hairs, and root nodules. They can 

 complete their growth on either roots or nodules, or both, but seem 

 to prefer the latter when they are available. They cut off roots and 

 devour a portion of a cut end and may gnaw some of the bark from 

 a larger root. When attacking nodules they cut a round hole into 

 the nodule and usually devour the entire contents, leaving only the 

 outer shell. They usually crawl out through the entrance hole 

 but may cut their way on through. Several small larvae may attack 

 a single nodule, making a number of entrance holes. One nodule has 

 been found to contain as many as 8 young larvae. The larvae usually 

 travel along the course of roots in search of fresh nodules, but may 

 go short distances through the soil. They have been found to injure 

 nodules as deep as 8 inches and over a foot in a horizontal direction 

 from the base of the plant. 



The larvae pupate in a nearly upright position in small earthen cells 



