91 



had perished in the sand in the larva or pupa state, and were not 

 counted. The Grand Total from 183 infested plums was, therefore, 

 134 Curculios in the beetle state, and an unknown number of larvie 

 and pupse. 



Experiment 2d. — On July 27th, or eight days before the Cur- 

 culios in the preceding experiment had ceased coming out, I placed 

 in a vase, similar to the above, 243 plums, gathered promiscuously off 

 some badly-infested wild plum-trees. From this lot no Curculio.'i 

 whatever came out till August 23d, and from that day until Sep- 

 tember l-lth more or less came out daily, with the exception of five 

 out of the 23 days, the numbers on the respective days being as fol- 

 lows : 3, 1, 2, 2, 2 , 3 , 2 , 2 , 5 , 3, 1 , , 5 ,, 6 , 3 , 2 , , , , 1 , , 1 , 1. 

 Subsequently, on September 18th, there came out 3, on September 

 24th, 1, and on September 28th, 1 ; after which no more made their 

 appearance. Total, 50 Curculios from 243 plums, some stung and 

 some not. On examining the contents of this vase on November 29th, 

 I found a single dead Curculio among the plums, making a Grand 

 Total of 51 Curculios bred from these plums. There were no speci- 

 mens, either in larva, pupa or beetle state, to be found among the 

 sand in the vase on November 29th; which was, perhaps, due to the 

 contents having kept much moister than those of the first vase, though 

 on July 25th I had, as I thought, moistened the sand in the first vase 

 quite sufficiently. 



The vases, in both the above two experiments, were examined 

 daily, and the results noted down in my Journal, except during a 

 three-days' absence from home, August 11th — 13th, at the end of 

 which time, however, not a single Curculio had come out. Since, 

 therefore, it appears that in large lots of plums, gathered or picked 

 up at various times from June 24th to July 27th, the Curculio ceased 

 coming out for a period of no less than nineteen days, before and af- 

 ter which period it continued to come out for a long while as regu- 

 larly as we could reasonably anticipate, the inference is unavoidable, 

 that there must have been some cause for the long intermission in its 

 coming out. But I do not see that it is possible to account for this 

 intermission on any other hypothesis, than that of there being two dis- 

 tinct broods. Therefore I infer that there are two distinct broods, 

 the second of which is, of course, generated by the first. 



The Curculios, bred from Black-knot in New England, by Prof. 

 Peck, in 1818, are said to have come out July 30th, and a little later 

 (Harris Inj. Ins., p. 79.) Those bred in Canada West, from the same 

 substance, by Mr. Beadle, in 1860, are said to have come out from 

 the beginning of July to August 10th. (Fitcli Address on Curculio, 



