446 



PSYCHE. 



[May 1S93. 



continuing the work itself. The slits 

 were about 1 mm. in length and were 

 always in the ventral suture, sometimes 

 almost at the point of attachment of the 

 seed. May 23, I found a cluster of eggs 

 in a cavity at one end of a pod, and later 

 two or three eggs were laid upon the 

 outside of the pod, but these were soon 

 knocked off by the beetles themselves in 

 running about. June 8 the eggs in the 

 cavity hatched. It was not until June 

 18, however, that I discovered the nor- 

 mal nidus of the eggs of obtectus. 

 Upon opening some of the pods I was 

 surprised to find clusters of eggs within 

 the pods attached to the ventral suture 

 at the point where I had seen the narrow 

 slit being made by the beetles. The 

 slits do not close up and disappear but 

 the tissues turn dark and the place is 

 thus readily seen in green and even in 

 riper pods. 



On August 15 I presented these facts 

 before the Association of economic 

 entomologists at Rochester (Ins. life, v, 

 86). Two days later before the Ento- 

 mological club of the A. A. A. S. (Ins. 

 life, v, 31), Dr. Riley reported similar 

 observations upon the oviposition of the 

 bean weevil in his garden at Washing- 

 ton, thus confirming my laboratory ex- 

 periments. It seems probable, however, 

 that Dr. Riley's observations were made 

 later than May or June, for in the 

 August number of the Canadian ento- 

 mologist, p. 186 he s^iys : "The eggs 

 are primarily laid upon the bean-pod in 

 the field, but chiefly, if not entirely, on 

 those which are already mature and 

 ripening, and the larvae enter the same 

 very much as does the pea weevil." 



The eggs (plate 16, fig. 1, b) are about 

 • 75 mm. in length and .3 mm. in diam- 

 eter at the widest part ; the color is 

 white and the surface finely granulate. 



In 1879, Dr. Riley discovered the 

 important fact that the insects continue 

 to breed for many generations in stored 

 beans. Although this very important 

 fact was published in a newspaper in 

 1882, it did not become known to most 

 entomologists until Dr. Lintner re- 

 corded similar observations in his 

 seventh report for 1890. During the 

 past year I have bred several genera- 

 tions of the beetles in the dry seeds. I 

 find that even in the slightly varying 

 temperature of an office, the season 

 notably affects their development. 

 When the eggs were laid in March 

 adults issued in about eighty days, 

 while in August beetles emerged from 

 beans upon which eggs had been laid 

 only thirty days before. The egg and 

 pupal stages are of about the same 

 length while the larval stage occupies 

 about twice as many days as either. 



Among dry beans the eggs are laid 

 on the seeds but are so slightly attached 

 that they are easily dislodged if the 

 seeds are disturbed. The egg shell is, 

 however, very strong and seldom 

 broken by the movement of the beans. 

 As Dr. Riley has shown (Ins. life, iv, 

 301) the newly hatched larvae (fig. 1, c, 

 adapted from Riley's figure) present 

 several interesting features not found in 

 its further stages. Its long slender legs 

 enable it to move quite readily over the 

 beans until it finds a suitable place, 

 when it bores a minute round hole 

 through the shell and enters the seed. 



