PROC. ENT. SOC. WASH., VOL. 53, NO. 1, FKBRUARY, 1951 25 presence may be attributed by the human host to (1) "imag-ination," as the doctors would have us believe; (2) "summer heat," since the mites are most active during hot weather; or perhaps (3) "dandruff." A wide-open field exists for any-one enterprising enough to do some real investigation on this subject. The presence of the mite BdcUoHyssu.s sylviarum as a causa-tive agent of dermatitis in the human scalp and on the human body is likewise reported. At last reports, the unfortunate host of this mite was still suffering from its depredations. In this case, the diagnosis had been: "Just a phobia." Here is another field in which to date there has been no competition in the matter of studying the mite as an occasional human parasite. THE GENUS PROBEZZIA IN NORTH AMERICA (DlPTERA, HeLEIDAe) By Willis W. Wibth, Bureau of Entomology and Plant Quarantine, U. S. Department of Agriculture The purpose of this paper is to call attention to the proper application of the generic name Prohezzia Kieffer, to present descriptions of four new species from the United States, to include notes and distribution records for the seven previously known species and to off'er a key for their separation. Most of the material studied is from the U. S. National Museum collection (abbreviated USNM in the distribution lists). Short series were also examined from the California Academy of Sciences (CAS) through the courtes,y of E. S. Ross and E. L. Kessel, from Curtis W. Sabrosky's collection of Michigan and Kansas Diptera, and from the writer's per-sonal collection from Louisiana and California. Genus Probezzia Kieffer Prohezzia Kieffer, 1906, Gen. Insectorum, fase. 42:n7; C*oquillett, 1910, Proe. U. S. Nat. Mus., 37:594; Malloch (part), 191-1, Proe. Biol. Soc. Wash. 27:137; Malloch (part). 1915, Bull. 111. St. Lab. Nat. Hist. 10:352. (Genotype: Ceratopogon venustus Meigen, desig. Coquillett, 1910). Dicrobezzia Kieffer, 1919, Ann. Mus. Nat. Hungarici 17:127; In-gram & Macfie, 1921, Ann. Trop. Med. and Parasitol. 15:371; Edwards, 1926, Trans. Ent. Soc. London. 74:414; Johannsen, 1943, Ann. Ent. Soc. Amer. 36:785; Lane, 1947, Arq. Fae. Hig. S. Pub. U. Sao Paulo 1:232. (Genotype: Ceratopogon reniisitus Meigen, orig. desig.). New synonymy. Diagnosis: Body slender and nearly bare. Eyes bare and usually well separated ; antennae with flagellar segments elongate, verticils short and sparse, in male with plumes scanty; palpi slender. Mesonetum with-out anterior spine or tubercle; dorsum with short scattered erect bristles.