48 



potted turnip and cauliflower. On the leaves of the former they fed 

 freely, but no punctures were made in the stems, and no eggs or larvae 

 were found in them, neither could they be found in hedge mustard 

 nor cauliflower, upon which the beetles had been seen. 



Owing to the difficulty in obtaining natural conditions for the cur- 

 culios in confinement, the exact periods of the different stages were 

 not obseryed; but from the facts ascertained we may deduce the life 

 cycle with tolerable exactitude, reasoning from analogy, the ascertained 

 data concerning other species. 



SUMMARY OF LIFE HISTORY. 



The following summary is based upon observations made in the 

 District of Columbia upon the Department grounds: 



The beetles make their first appearance some time in April and 

 begin the depositing of their eggs, selecting by preference for the 

 purpose wild-growing plants, such as hedge mustard. The parent 

 beetle, after copulation with the male, punctures the stem of the host 

 plant while the plant is still young, inserting her eggs in the holes 

 made. It seems probable that oyiposition begins some time about the 

 middle of April, and continues at least a month, the parent insects 

 practically all dying and disappearing by the end of May, as only one 

 or two stragglers could be found by sweeping infested patches after 

 that time. 



The egg period will vary slightly, as do all the periods, according 

 to the temperature, between five and eight days being the approxi- 

 mate time. The larvae feed within the stems and larger leaf-stalks, and 

 in about three weeks complete their growth, cut their way out, usually 

 near where the leaf -stalks join the stem and enter the earth. Just 

 beneath the surface of the earth they form little round earthen cocoons, 

 and within these remain for about two weeks longer before forming 

 the pupa. The pupal period is about the same as the egg, five to 

 eight days, when the mature beetle is formed and cuts its way through 

 one end of the cocoon and issues above ground. The first pupa 

 obseryed was found May 20, and the first imago appeared June 3 in 

 its cocoon. Within ten days later most of the beetles had made their 

 appearance in the infested locality, all at this time being readily recog- 

 nizable from the hibernating specimens by their darker tawny color. 

 On the Department grounds none of the first or hibernated generation 

 could be found at this time, consequently there was no overlapping 

 of generation. The beetles had all deserted their wild plant by the 

 end of the middle of June, but were still present on cauliflower and 

 cabbage June 21. 



A noticeable feature of the observations on the Department grounds 

 was that cabbage, which was set out purposely in the immediate vicin- 

 ity of the hedge mustard, showed no signs of infestation from the 





