BIRCH TREE HOPPER Carynota stupida Walker This species (Plate III) often occurs in large on yellow birch, but its presence world scarcely be suspected since the insert is so perfectly protected by form and color that it is hardly possible to see them even when their position has been noted.
The nymphs occur almost invariably in the axih; of small twigs, mostly on branches of one year's growth, the head pressed closely against the base of the twig, the body lying tlat and lengthwise on the branch, the tail usually toward the tip of the branch (Fig. k, Plate III). Here they remain apparently for long periods of time, the food supply being drawn doubtless from the cambium of the growing twig. They are very commonly attended by ants, so far as observed all of one species (Formica sumo:Iva Latr. sub. sp. cubic-uncle Emery*) ; and by far the easiest way to locate the nymphs is to look for the ants and note the nymphs which they are attending. The nymphs appear absolutely oblivious to the movements of the ants, .although the frequent rubbing and " caressing " which they receive would seem to be sufficient to disturb them. The nymphs, however, appear to he very difficult to disturb, seeming to be glued to the twig. and only forcible action will ordinarily dislodge them. The adults arc almost equally difficult to move (possibly the basis for Walker's name stupida), no doubt having become fully adapted to depend ence on their protective features to escape enemies. The human enemy is, of course, an entirely negligible factor in the immense solitudes of the great birch forests and especially in the tree tops, but the prying eyes of insectivorous bicds may well be deceived by the perfection of the resemblance displayed.
The attraction for the ants lies in the liquid discharge from the anus, no doubt comparable to the " honey clew " of aphids, and the constancy of the association would indicate that the ants make a large use of this food supply during the period of life of the tree-hoppers. When aphids are also present the same' ants appear to visit either aphid or tree-hopper.
The species was first described by Walker from specimens received from Canada ( ?) but with no description of early stages. Later descriptions by Butler, Provancher and Goding, none of which go into details of the life history or habits, have evidently been based on limited material appearing in collections.
It is not at all strane.e that specimens have been rare since the species is adapted to life in a manner which precludes its frequent collection. In the primitive forest or on all larger trees the insect occurs probably only on the outer part of branches in the upper part of the tree, or at least far from easy capture by the entomolo gist. Only the fortunate occurrence of numerous young yellow birch trees in a. ent-over and burned tract at the State Forest Camp has furnished the opportunity to note the mode of life and stages of growth which apparently have escaped the attention of entomologists up to the present.