Specimens of a new species of Trombicula were collected on Bougainville Island by J. M. Fritts, PhM2c, during the summer and fall of 1944. These specimens are described under the name Trombicula frittsi. Womersley and Heaslip (1943) devised a series of standard measurements of the scutum. Their system is adopted and the designations of the measurements follow: AW-distance between the bases of the anterior-lateral setae. PW-distance between the bases of the posterior-lateral setae. SB-distance between the centers of the pseudostigmata. ASB-greatest perpendicular distance from a line drawn through the centers of the pseudostigmata to the anterior margin of the scutum. PSB-greatest perpendicular distance from a line drawn through the centers of the pseudostigmata to the posterior margin of the scutum. AP-distance between the bases of the anterior-lateral and posterior-lateral