22 



Lines also run from the base of the antennae to the mandibles. The slender antenna3 

 are dark at the base but get lighter toward the tip. The thorax and abdomen are dark 

 brown, ornamented witli lines and borders of yellow, which is also the colour of the legs. 

 The wings (front pair) expand from one and one-quarter to two and one-half inches, and 

 have a quadrangular dark patch on the anterior border. 



The larvffi of both " long-stings" feed upon those of the Uroceridoe and other wood- 

 borers, in whicii the female ichneumon deposits her egg^i by means of the Ion,' ovipositor. 

 The method of performing this operation may often be witnessed during the summer by 

 visiting beech trees in which Tremox larvae are at work, but it is difficult to describe 

 clearly its accomplishment and the different postures of the insect during the progress 

 of her laborious and dangerous duty. A series of good drawings would best convey a 

 correct idea of the process, but I do not know of any book in which such are to be 

 found, while some illustrations are very inaccurate. For instance, I saw the other day 

 in a text book of zoology an ichneumon depicted with her ovijjositor fully inserted in the 

 tree and with the side- pieces or sheatlis stickiiKj straight out behind her. Such an attitude is 

 altogether unnatural, and I am convinced that in that position she would be powerless 

 to extract the ovipositor. 



Selecting a suitable tree, if we find no ichneumons at work, we may shortly see one 

 flying strongly and noisily through the sunny woods and settling upon the bark where 

 perforations mark the exits of previous occupants. Hero she runs around until she 

 finds a promising spot, as, for instance, the hole made by a Tremex in depositing her 

 egg. Placing hersulf so that the tip of her abdomen will be above the orifice to be 

 probed she makes herself as tall as possible, and, by elevating her abdomen and curving 

 under the ovipositor, succeeds in inserting the tip of the latter in the hole. 



If the dorsal surface of the abdomen be examined, there will be observed, between 

 the sixth and seventh segments, a gap closed by a whitish membrane. This marks an 

 admirable contrivance to enable the insect to use her seemingly unwieldy weapon, for 

 the membrane is capable of being so dilated as to form a cavity in the posterior part of 

 the abdomen, in which can be coiled a largo portion (more than one-third) of the 

 ovipositor, which thus becomes perpendicular under the insect, where it is guided and 

 supported by the sheaths which bond up in loops over her back. By vigourous muscular 

 contractions of the sac, the delicate ovipositor is slowly forced down the larva's burrow, 

 often to its full extent. If a larva be reached an egg is deposited in it, and the oviposi- 

 tor is slowly withdrawn in a similar manner. This, however, the insect is frequently 

 unable to accomplish, and remains struggling until some bird or tree-toad snaps her up, 

 or she perishes from exhaustion. 



I have seen a large li. atrata with her ovipositor (five and one quarter inches long) 

 inserted four and one-half inches into a beech, so firmly that it was only by careful and 

 vigourous pulling that I extracted it uninjured. 



The insects are to be found during the latter part of the summer; R. btnator, as al- 

 ready mentioned, being much the more abundant. 



On tbe last day of June, 1879, while collecting in a grove just beyond Rideau Hall, 

 I stopped to examine a dead tree for bark and fungi beetles, and was bottling a fine 

 Penthe pimelia, when the rustling of insect wings above ma attracted my attention. Look- 

 ing up I saw several specimens of lutiator flying about the trunk, and a circuit of the 

 tree with closer inspection showed many others walking about on the bark or in various 

 stages of tlie act of ovipositing. The tree was a large one, about two feet in diamter, 

 from wbicli the top had been broken oli' at a height of thirty or forty feet. The rugged 

 bark was dotted all over with Iniuitors, often massed in rows or patches, so that there 

 must have been several hundred upon the tree, forming an unusual and most interest- 

 ing spectacle. The great majority were females, but a number of males wore also pre- 

 sent. While I was consigning to my bottle a f3W specimens, a largo woodpecker settled 

 upon the opposite side of the tree and began to r.ipidly thin the rank's of the helpless in- 

 sects, whose mission, like that of the woodpecker, is the destruction of wood-boring 

 larvae. 



A year later, being in the same locality, I visited this tree and found again a num- 

 ber of ichneumons engaged in the performance of their duty, and also saw sticking out 



