72 



FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



Prof. Riley found this insect boring in the wood of a rotten oak- 

 stump in May, 1872, at St. Louis, Mo. 



The bark called quercitron, of the Qiiercus 

 tinctoria, is highly valued as a dye, and is much 

 worm-eaten by this insect. 



<r:) 



Fig. 22. — Graphisurus fascia- 

 tus, female. Smith, del. 



The parent of the worm dififers remarkably from all the 

 other beetles of this group in that the female is furnished 

 with a straight awl-like ovipositor nearly a quarter of an 

 inch in length, projecting horizontally backwards from 

 the end of her body. The importance of this implement 

 becomes manifest when we observe the thickness of the 

 bark of the black oak, with its outer layers so dry and 

 hard that they form, as it were, a coat of mail, protecting 

 the trunk of the tree against the attacks of its enemies. 

 Equipped as she is, however, the female of this beetle is 

 able to perforate this hard outer bark and sink her eggs 

 through it, placing them where her young will find them- 

 selves surrounded with their appropriate food. The 

 worms from these eggs mine their burrows mostly length- 

 wise of the grain or fibers of the bark, and the channels 

 which they excavate are so numerous and so filled with 

 worm-dust of the same color with the bark that it is diffi- 

 cult to trace them. The eggs are deposited the latter part of June, and the worms 

 grow to their full size by the close of the season, and will be found during the winter 

 and spring, lying in the inner layers of the bark, in a small oval flattened cavity 

 about an inch in length, which is usually at the larger end of the track they have 

 traveled. 



The larva is divided by transverse constrictions into twelve rings, the last one 

 being double. The head is small and retracted more or less into the neck, its base 

 white and shining, audits anterior part deep tawny yellow, and along each side black. 

 The neck or first ring is much longer as well as thicker than any of the others, the 

 two rings next to it being shortest. From the neck the body of the worm is slightly 

 tapered backwards to the middle, from whence it has nearly the same diameter to the 

 tip, where it is bluntly rounded. Upou the upper side of the neck, occupying the 

 basal half of this ring, is a large transverse tawny-yellow spot, rounded upon its for- 

 ward side ; but no corresponding spot appears on the under side of this ring. On the 

 middle of all the other rings, except the two last, both above and below, is an ele- 

 vated, rough, transverse, oval spot of a tawny-yellow color. 



The beetle, like other species of the family to which it pertains, varies greatly in 

 its size, specimens before me being of all lengths, from 0.35 to 0.58. It is of an ash- 

 gray color from short incumbent hairs or scales, which have a faint tinge of tawny 

 yellow except along the suture of the wing-covers. It is also bearded with fine erect 

 blackish hairs which arise from coarsish black punctures which are sprinkled over 

 the thorax and wing-covers, several of which punctures are in the centre of small 

 black dots, which in places are couflueut into small irregular spots. The head is of 

 the same width as the anterior end of the thorax, and has a deep narrow furrow along 

 its middle its whole length, and on the crown is an oval blackish spot on each side of 

 this furrow. The face is dark gray, and the antennae are black with an ash-gray band 

 occupying the basal half of each of the joints. The thorax is narrower than the 

 wing-covers, more broad than long, and thickest across its middle. Upon each side 

 slightly back of the middle is an angular projection or short broad spine, blunt at its 

 tip. On the middle of the back, between the centre and the base, is a short im- 

 pressed line, and on each side of this, extending the whole length of the thorax, is a 

 wavy blackish stripe, which is suddenly widen-^d towards its hind end, and is some- 



