In the realization that all exact field experimentation and census work with insects is dependent upon accurate recognition of the species involved, a study of the comparative external morphology of the larvae was planned, from the first. as an integral part of the major project on wireworms, which was incepted in 1922, at the Dominion Entomological Laboratory, Saskatoon, Saskatchewan. The soundness of this viewpoint has been amply demonstrated, in that the morphological work has repeatedly proved to be vital to the whole economic study of this pest, which is being increasingly recognized (King, 1928; Seamans, 1933) as one of the major problems of wheat-growing in western Canada.

Horse flies of the genus Tabanus are among the most persistent and annoying of the blood-sucking pests affecting Utah livestock. Tn many areas of this state they are particularly troublesome to cattle and horses during much of the summer and fall. The intermittent feeding habits of the Tabanidae at once mark them as potential vectors of disease. This study has been undertaken as a part of the investigation of the role of blood-sucking insects in the transmission of equine encephalomyelitis.

On June 17, 1934, three or four green cones of Pinus ponderosa Dougl. were collected which showed some insect damage.

Upon examination, almost mature larvae of this Dioryctria were observed to have eaten away practically the entire inner portion of the cone, leaving the axis and the outer portion.attached at the top and bottom so as to form a rather large retreat.

Of the two moths obtained, one emerged June 26 and the other June 29, 1934.