CULEX EQUIVOCATOR 327 



ment of many spines in a triangular patch ; single spine elongate, widened out- 

 wardly, fringed with spinules around tip. Anal segment as long as wide, ringed 

 by the plate ; dorsal tuft a group of long hairs on each side ; a single lateral hair ; 

 ventral brush well developed, confined to the barred area; anal gills a little 

 longer than segment, father broad and rounded, showing a slight central trachea. 

 The larvae live in the water in the holes of certain species of crabs along the 

 sea-shore. Our collectors have found them in such situations and Mr. Busck 

 obtained the type-material from a bucket used to keep living crabs. He later 

 observed the species in its natural habitat and says : 



" The larvse of this species were taken in crab-holes, and the species is clearly 

 closely associated with these crabs, the adults remaining in the holes during day 

 time, like those of the genus Deinocerites. A large series was bred, but neither 

 adults nor larva were obtained in other localities." 



The adults apparently do not suck blood. Concerning the relation of these 

 insects to their hosts, Mr. Busck tells us that the larvge and adults are found in 

 holes actually inhabitated by the crabs. Generally each crab has its own hole ; 

 but it is difficult to find an untenanted hole, for if the owner dies, another crab 

 takes his place. These holes are deep, often several feet, with water in the bot- 

 tom. The crab fits closely into the hole, although on account of its flattened 

 shape there is some space above and below the crustacean, the hole being circu- 

 lar. The crabs rush to their holes with great rapidity, but once within descend 

 more slowly, on account of the narrowness of the hole. The adult mosquitoes 

 rest within the holes, and fly out on the approach of the crab, being doubtless 

 continually alert for its advent. The larvae find abundant nourishment in the 

 water in the bottom of the hole, enriched by the excrement of the crab. They 

 seek the bottom when disturbed, and in this way avoid hann while the crustacean 

 is in his domicile. Some of the females before us have the abdomen distended 

 with food and of a pale amber color, showing that the food was not vertebrate 

 blood. 



Trinidad to Central America, probably all along the northern coast of South 

 America. 



Cedros, Trinidad, June 23, 1905 (A. Busck) ; Colon, Panama, July 20, 1907, 

 associated with Deinocerites melanophylum and Dinomimetes epitedeus (A. 

 Busck) ; Caldera Island, Porto Bello Bay, Panama, January 19, 1908, asso- 

 ciated with Dinomimetes epitedeus (A. H. Jennings) ; Caldera Island, April 11, 

 1908, adults taken in crab-holes (A. H. Jennings) ; Ancon, Canal Zone, 

 Panama, August 9, 1908 (A. H. Jennings) ; Port Limon, Costa Eica, Sep- 

 tember 24, 1905, adults taken at crab-holes (F. Knab). 



CULEX EQUIVOCATOR Dyar & Knab. 



Culex equivocator Dyar & Knab, Journ. N. Y. Ent. Soc, xv, 203, 1907. 

 Culex equivocator Busck, Smiths. Misc. Colls., quart, iss., lii, 67, 1908. 

 Culex equivocator Theobald, Men. Culic, v, 614, 1910. 



Original Descbiption of Culex equivocatob: 



5. Proboscis rather long and slender, very slightly enlarged towards the apex, 

 black scaled: palpi short, black scaled; occiput brown scaled with bronzy luster, the 

 ocular margin very narrowly white scaled; mesonotum uniformly rich brown scaled 

 with bronzy luster; metanotum light brownish; abdomen depressed, truncate at the 

 tip, clothed above with brownish-black scales with faint bluish luster, the segments 

 with lateral white triangular basal spots, most distinct on segments 5, 6 and 7, 

 beneath black, the bases of the segments with broad soiled white bands; legs dark 

 with bronzy luster; claws equal and simple; scales of the wing-veins brown, long 

 and narrow througliout. Length, 3.5 mm. 



c?. Palpi longer than the proboscis, the two terminal segments with long hairs, 

 entirely clothed with deep-brown scales, without pale rings; abdomen with narrow 



