76 



THE AMERICAN ENTOMOLOGIST. 



of 1868, will do the usual amount of damage. 

 But, as in the last fifteen years there have been 

 only six Grasshopper invasions, the chances are 

 three to two against any fresh invasion occurring 

 in the autumn of 18C'J; and the same mode of 

 reasoning will equally apply to any subsequent 

 autumn. 



THE TWIU-GIRDLER, 



{t)nrii/rr/\'i ciu(/itlfftits, S'tif.) 



We have been puzzled for a long time, as our 

 readers may see from the Answers to Correspon- 

 dents on page 57 of our last number, to know 

 what insect it is that girdles and occasionally am- 

 putates the twigs of various trees in the manner 

 shown in the following engrav- 

 ing (Fig. 66 c). The mystery 

 las at length been solved by one 

 of our correspondents, Mr. Geo. 

 Hurnside of South Pass, 111., 

 detecting the culprit in the very 

 ait. Ui)on examining two spe- 

 cimens kindly sent to us by that 

 griitleman, the girdling insect 

 lovcs to be one of the rarest of 

 our Capricorn or Long-horn 

 Itcctles (the Oncideres cimjula- 

 /»sof Say, Fig. 66 a). And now 

 that we have been thus enabled 

 to recognize the species, we 

 find that, so far as regards the girdling of 

 hickory twigs by this beetle, the discovery was 

 made and published more than thirty years ago 

 by Prof. Haldeman*. Possibly the amputation 

 of pear-twigs, and especially of persimmon- 

 twigs, which we have ourselves noticed to 

 be so very connnon in South Illinois, in con- 

 sequence of such girdling, may be etfected 

 by a distinct species ; but, as Mr. Burn- 

 side says, that he discovered the very same 

 insect, which he had seen actually girdling 

 hickory-twigs, "under very suspicious circum- 

 stances" upon a pear-tree, the probability is 

 that it is the same species that operates upon 

 all these three trees. 



The Twig-girdler, according to Prof. Halde- 

 man, "may be seen in Pennsylvania during the 

 two last weeks in August and the first week in 

 September, feeding upon the bark of the tender 

 branches of the young hickories. Both sexes 

 are rather rare, particularly the male, which is 

 rather smaller than the female, but with longer 



* See his ftrticles on the Histoi-v of the Longiconi beetles 

 2, and in the 

 I Journal for 1851, 



ngic 

 Philoa. Transactlom for 1837, 1). 52, 

 851, p. U. 

 Parker Earle, ot South Pass, III., has since infoi-med 



> that he found the same beetle on an amputated pear twig. 



antennae. The female makes perforations (Fig. 

 66 b) in the branches of the tree upon which 

 she lives, which are from half an inch to a 

 quarter of an inch thick, iu which she deposits 

 her eggs, (one of which is represented of the 

 natural size at Fig. 66 e.). She then proceeds 

 to gnaw a groove, of about a tenth of an inch 

 wide and deep, around the branch and below 

 the place where the eggs are deposited, so that 

 the exterior portion dies and the larva feeds 

 upon the dead wood." 



In all the cases noticed by Prof. Haldeman, 

 the tree attacked was the Shagbark Hickory ( Crt- 

 rya cilb(t) and the twig was girdled so shal- 

 lowly, as not to fall oft' until after the lar- 

 va had matured within it, or nearly a year 

 after the girdling. " Then", as he subjoins, 

 "the decaying portion which is not eaten 

 by the larva is apt from its tender attach- 

 ment and the rapidity of decay to drop oft'." The 

 evidence of Mr. Benj. II. Smith, of Upper Dar- 

 by, Penn., who has kindly sent us specimens 

 both of the insect and of its work, is to the same 

 eft'ect. For he says tliat it does not attack any 

 tree but the hickory, and that it never cuts deep 

 enough to cause the limbs to fall oft'. But 

 in most of the cases which we have ourselves no- 

 ticed upon pear and persimmon trees, the twig 

 was girdled so deeply that it broke oft' and fell 

 to the ground with the first wind, and while the 

 eggs that had been laid in it by the mother-beetle 

 were still unhatched. Even in a girdled hickory 

 twig thirty-five hundredths of an inch in diame- 

 ter, which we have now lying before us. but a 

 third part of its diameter is left in the middle 

 ungnawed away ; so that in spite of the superior 

 toughness of this timber the twig could scarcely 

 have stood a high wind without breaking ott 

 and falling to the ground. 



It is worthy of remark that a European species 

 belonging to the same genus (Oncklerex ampii- 

 iator) has the same remarkable habit of ampu- 

 tating small branches; although European ob- 

 servers failed to discover the eggs in the ampu- 

 tated parts, and were thus unable to explain the 

 object of the proceeding. 



Nothing surprises us more in the natural his- 

 tory of the American Twig-girdler than the 

 great number of eggs that may sometimes be 

 found in one amputated branch. In a persim- 

 mon branch not more than two feet long, we 

 have counted as many as eight, eggs, placed one 

 under each successive side-shoot ; and we have 

 found seven eggs all crowded together in a small 

 hickory branch only three inches long. Now, 

 judging from the amount of timber consumed 

 by the larva) of other boring beetles before they 



