During the past summer the Locust Mite (Trombidum locustarum, Riley) has been very common at Guelph, especially on the Red-legged Locust (Melanoplus femur rubrum), but a few specimens have also been found upon the Two-striped Locust (Melanoplus bivittatus). The mite is most generally found attached to the base of the second pair of wings, although it is alos found on the wing itself, and on any other part of the body where it cannot be readily detached by the locust; a favourite position upon the body is between the segments of the thorax and abdomen, and also behind the upper joints of the legs; in such postion their only means of attachment to their host is apparently by theri mandibles.