THE APPLE-TWIG BORER: I.IFE-HISTORY. 



127 



Habits of the Insect. 



The habits of this little borer are ])eculiarly interesting, from the fact 

 that it is the mature insect that inflicts the injury by boring the twigs 

 instead of the grub or larva, which is the usual depreda- 

 tor. Its method of attack is as follows: Just above a bud, 

 III at a point from six to twelve inches from the tip of the 

 twig, it gnaws a hole of about one-twelfth of an inch in 

 diameter (the size of its body), and burrowing therein 

 passes downward into the heart of the twig for the dis- 

 tance of an inch or an inch and a half, or occasionally 

 upward, as represented in Fig. 29. This is done soon after 

 i|the beetle emerges from the pupa state during the months 

 of May or June, for the purpose of feeding and for shel- 

 ™ ter, and not, as would naturally be supposed, to provide a 

 suitable place for the deposit of its eggs. Both of the 

 sexes, it is said, are found within these burrows, and 



Fic. 29.— Biiii-ow • 1 1 



of AMi'HicERus III- always with the head turned from the opening — a reverse 



C.VUDATIS 111 iipple- -'_ I & 



^'^'^'^^- position from that which would follow their pupation 



within the twig and provision for tlieir subsequent escape through the 

 opening. 



Life-History. 



Of the early stages but little is known. Judging from the range of 

 food-plants which the beetle allows itself, it is probable that the larvae 

 will prove to have a corresponding range. Thus far it is known only 

 to breed in grapevines, from which it has been reared by Dr. Shinier. 

 Larva) sent by him to Dr. Packard, which had been taken from grape, 

 were " much the same form as Ljjcliis, but the head is more prominent 

 and also the sides of the body. The anterior half of the body is con- 

 siderably thicker than behind, and the legs are provided with long 

 hairs ; the end of the body is smooth and much rounded. It is 0.30 of 

 a:"i inch long."* 



"Is there still room for questioning a grapevine food-plant for this larva '? In 1872, Prof. 

 Tiiley wrote in reference to it: " The probabilities are that Dr. Packard's description [above 

 quoted] was in reality from this last-named species" \Si)ioxi/lon basilare] {ith Mo. Re- 

 port, p. 52). In 1873, Dr. Shinier having communicated the fact that he had found a note 

 attached to an example of A. hicaudatus, of its having been bred from grapevine, Prof. 

 Uiley concedes that it "substantiates the statement in Pack.ird's 6'«i(/(,', giving at least 

 one known food-plant for the larva, and proving the great similarity between it and that 

 of Sifio.tijlon basilare Say" (oi/t Jfj. Report, p. 51). In 1330, we have this statement un- 

 der a notice of A. bicaudalus : " The breeding habits of the insect are not yet known with 

 certainty, for while Dr. Henry Shimer found certain larv:e in grapevines which he con- 

 jectured to be of this species, yet they were doubtless those of an allied beetle Sinoxylon 

 b'l-iilareSAy.— C V. R. in A^eiv York Tribune" {American Entomologist, iii, 1880, p. 51). 



