41 



eye, above which (and within the ring) is a small oblique white line. There is also a 

 minute white dot at the base of each antenna, with a large almost square one above it. 



The thorax is strongly roughened, with a triangular white patch enclosing a black 

 dot on the shoulder, and two small spots on the back between the hinder pair of wings. 

 The wings, four in number, are almost transparent, but have a very faint smoky tinge. 

 The abdomen is jet black, with the exception of spots on each side, varying in number 

 from four to six, and in size from spots to semi-bands ; that on the posterior segment 

 being the longest. The ovipositor is contained in a flattened scabbard projecting only 

 slightly beyond the tip of the body, as about two-thirds of it are concealed within the last 

 segment which is grooved to receive it. The full length of the ovipositor is one-fifth to 

 one-fourth of an inch. 



The male is slightly smaller than the female and more variable in colour, having 

 the antennae generally black, but differs essentially only in the abdomen, which is more 

 flattened and rounded at the tip — lacking of course the ovipositor. It is very much 

 more rare than the female ; ten of the latter being observed for one of the former. 



Having now sufficiently described the insects to ensure their recognition, there 

 remains the consideration of their habits. The specimens mentioned at the beginning 

 of this paper were taken on a tree which had recently died, and althoiigh one was in the 

 act of ovipositing in the bark, no particular attention was given to the fact, as dead 

 trees naturally become the prey of various species of insects, many of which may not 

 attack them when living. A. few days later, however, I found a third female upon a 

 living tree, and having an interest in the Uroceridje (to which group these insects 

 belong), I determined to make further investigations concerning them this summer. 



The result shows that the insect is far from being so rare as I then considered it, 

 and that it must do no little damage to our maples, to which trees it seems to entirely 

 confine its operations. Occasionally I have found it upon dead trees, but have usually 

 observed it upon living ones ; not only on those that are old and hastening to decay, 

 but upon those that are young and presumably vigorous. Specimens were observed 

 almost daily from the middle of June to the end of July, on shade trees in the city, or 

 on trees in the neighbouring woods. 



In the city the trees attacked were usually of small or medium size, and the pref- 

 erence thus shown by Xiphydria for young trees 

 seems only natural when we consider its structure. 

 Our other maple horntail {Tremex columha, figure 10) 

 is a large powerful insect, armed with an ovipositor 

 long and strong enough to deposit its eggs through 

 the bark even of old and rough trees, and it is upon 

 such trees, usually when they commence to decay, 

 that it is found. Xiphydria, on the other hand, is a 

 comparatively small and feeble insect, with a short 

 weapon fitted only to pierce the thin and softer bark 

 of the younger trees. It may be occasionally found 

 upon old trees, but it is then nearly always rambling 

 about, as if unable to find a suitable spot for deposit- 

 ing its eggs. 



Fig. 10. On a tree not more than two or three inches in^ 



diameter I have seen as many as eight ovipositing a 

 the same time, and have frequently observed two or three at once upon small shad® 

 trees. Tremex in its endeavours to oviposit through the tough, thick bark of the old 

 trees, frequently fails in withdrawing its ovipositor, and scores of such self-immolated 

 martyrs to the propagation of their race may be seen in the autumn dead and dry- 

 This is a fate that rarely befalls Xiphydria ; indeed I have only met with one instance 

 of a dead specimen thus anchored. Hence this insect will in many instances deposit 

 successfully a much larger proportion of its eggs than can its larger relative, and thus 

 stands a better chance of rapidly increasing the species. 



Not having been able to cut into any of the infested trees and examine the larvae, I 

 am unfortunately unable to describe them. The grubs of this genus are, however, said 



