THE AMERICAN ENTOMOLOGIST. 



135 



0111- rnelous aud our cucumbers, and prefents 

 its ghastly self even in our choicest pickles. 

 The "Struggle for Life " causes many a vacil- 

 lation in the proportion of an insect and its 

 parasite — the cannibal and its prey— and the 

 Little Turk may yet find his match in this 

 apparently insignificant Thvipa. 



Mooted Points, 



We will now brictly touch upon a few points 

 on which there is ditference of opinion, and 

 which will, it is to be hoped, elicit discussion, 

 and draw out the opinions and experience of 

 those present. 



There is conflicting evidence from ditlerenl 

 authors, as to whether the Curculio is single or 

 double brooded each year, and as to whether it 

 hybernates principally in the perfect beetle state, 

 above ground, or in the preparatoi'v state, below 

 ground; the very earliest accounts we have of 

 the Plum Curculio, in this country, diflering on 

 these points. Thus, it was believed by Dr. 

 .James Tilton, of Wilmington, Delaware, who 

 wrote at the very beginning of the present cen- 

 tury, and by Dr. .loci Burnett, of Southborough, 

 and M. H. Simpson, of Saxonvillc, Massachu- 

 setts, who both wrote interesting articles on the 

 subject, about fifty years afterwards ; that it 

 passed the winter in the larval or grub state, 

 under ground, and Harris seems to have held 

 the same opinion. But Dr. E. Sanborn, of 

 Audover, Massachusetts, in some interesting 

 articles published in 1849 and 18o0, gave as his 

 conviction that it hybernates in the beetle state 

 above ground. Dr. Fitch, of New York, came 

 to the conclusion that it is two-brooded, the 

 second brood wintering in the larva state in the 

 twigs of pear trees; while Dr. Trimble, of New 

 Jersey, who devoted the greater part of a large 

 and expensive work to its consideration, decided 

 that it is single-brooded, and that it hybernates 

 in the beetle from above ground, and he recently 

 informed me that he still holds to the same 

 opinion. Since the writings of Harris and Fitch, 

 and since the publication of Dr. Trimble's work 

 there have been other papers published on the 

 subject. The first of these was a tolerably ex- 

 haustive article, by Mr. AValsh, which appeared 

 in No. 7 of the 2nd Volume of the Practical 

 Entomologist, in which he takes the grouuds 

 that the Curculio is single-brooded; though 

 subsequently, on page G7 of his First Annual 

 Report, he came to the very different conclusion 

 that it was double-brooded. In the summer of 

 1867 I spent between two and three weeks in 

 Southern Illinois, during the height of the Cur- 

 culio season, and closely watched its manceii- 



verings. From the fact that there was a short 

 period about the middle of ,Tuly, when scarcely 

 any could be caught from the trees, and that 

 after a warm shower they were quite numerous, 

 having evidently just come out ot the ground, 

 I concluded that the insect was double-brooded, 

 and communicated to the Prairie Farmer of July 

 27th, 1867, the passage to that efiect, under the 

 signature of " V," which is quoted by Mr. Walsh 

 (Rep., p. 67), as corroborative of its two-brooded 

 character. Subsequent calculation induced mc 

 to change my mind, and I afterwards gave it as 

 my opinion, on page 11:5 of the Transactions of 

 this Society for 1867, that there was but one 

 main brood during the year, and that where a 

 second generation was produced it was the ex- 

 ception. My reasons for this opinion may be 

 found detailed in the Missouri Entomological 

 Report. Finally, our friend. Dr. Hull, of Alton, 

 Illinois, who has had vast personal experience 

 with this insect, read a most valuable essay on 

 the subject, before the meeting of the Alton (111.) 

 Horticultural Society of March, 1868, in which 

 he evidently concludes it is single-brooded, and 

 that it passes the winter, for the most part, in 

 the preparatory state, under ground ; aud judg- 

 ing from an article recently published by him 

 in the Prairie Farmer, he yet inclines to the 

 same belief. 



Now, why is it that persons who, it must be 

 admitted, were all capable of correct observa- 

 tion, have differed so much on these most in- 

 teiesting points in the economy of our Plum 

 Curculio? Is there any explanation of these 

 contradictory statements? I think there is, and 

 that the great difllculty in the study of this, as 

 well a^ of many other insects, lies in the fact 

 that we are all too apt to generalize. We are 

 too apt to draw distinct lines, and to create 

 rules which never existed in Nature— to suppose • 

 that if a few insects which wc chance to watch 

 are not single-brooded, therefore the species 

 must of necessity be double-brooded. We for- 

 get that Curculios are not" all hatched in one 

 dav, and, from analogy, are very apt to under- 

 rate the duration of the life of the Curculio in 

 the perfect state. Besides, what was the excep- 

 tion one year may become the rule the year 

 following. In breeding butterflies and moths, 

 individuals hatched from one and the same batch 

 of eggs on the same day, will frequently, some 

 of them, perfect themselves and issue in the fall, 

 while others will pass the winter in the imper- 

 fect state, and not issue till spring; and in the 

 case of a prangling green worm that is found 

 on raspberry leaves, and that passes the winter 

 under ground, aud develops into a four-winged 



