274 Forty-fourth Report on the State Museum 



testa (shell) of the ripened and dried bean without the need of a 

 fracture, or puncture such as was made for it in the present instance. 

 But that this may be done — if we may judge from the number of dead 

 larvae observed, and on the supposition that they were from eggs 

 deposited upon the sides of the box — it is highly probable that the aid 

 given the larva by the walls of the egg-shell while still within it, in 

 concentrating, guiding, and sustaining its muscular efforts, or that 

 afforded by some surface in contact, as of an adjoining bean or the 

 inclosing bag or jar, is essential to its effecting an entrance. That the 

 punctures made in two of the beans, as previously stated, were utilized 

 by the traveling larvae, appears from the fact that they contained the 

 largest number of beetles, viz., eighteen and nineteen, as against an 

 average of five in the others. 



The lid, cut by the beetle for its release. — The exit of the Bruchus 

 through a circular or oval neatly-cut lid, evincing so much design in 

 its construction, has been stated by numerous writers. Over a century 

 ago the* distinguished French entomologist, Olivier, had represented 

 the larva as cutting a channel to the outer covering of the seed, and 

 leaving it so thin that the slightest effort suffices to open it. Dr. Harris 

 repeats the statement. Dr. Packard, more recently, has w^'itten : "The 

 insect escapes through a thin orbicular almost transparent lid, prev- 

 iously gnawn by the larva, which falls when the beetle emerges." 



That the lid is made by the larva seems to have been accepted by 

 all who have written of it. It is, however, not formed at this stage of 

 the insect's life, but later, by the beetle. The larva, guided by instinct, 

 carries its burrow outwardly quite to, and partly within, the shell, 

 where a semi-transparent irregular spot in which the burrow termi- 

 nates locates the proper place for the pupal cell. Here the cell is 

 made and pupation follows. When the final transformation has taken 

 place the beetle commences to feed at the ruptured end of its cell, 

 and eats into the shell — not at the semi-transparent spot above- 

 mentioned, but removed a little way therefrom, perhaps slightly more 

 than the cell's length. 



The first indication of the construction of the lid is a small trans- 

 lucent crescent, rather sharply defined on its convex side. The 

 crescent continues to grow in size and to extend the measure of its 

 limb and the, translucent portion within, paralleling the increase of 

 the growing moon, until, like that, it becomes full-orbed. The few 

 adhering grains of the body of the shell are next dissected away, and 

 finally, when the time for emergence has nearly come, a cutting is 

 made into the lid around its entire circumference, leaving it attached 

 by hardly more than a film, This, of course, is done by the man- 



