OF WASHINGTON, VOLUMK XIX, 1917 141 



(Cephus) Janus rufiventris (Cresson) . 



Konow leaves this species in Cephus, but'Dr. J. C. Bradley who 

 has examined the type, which is Cat. No. 534 Acad. Nat. Sc. 

 Phil!, has kindly permitted the writer to state that the species 

 belongs to the genus Janus. 



A PECULIAR HABIT OF A HORSEFLY (TABANUS AMERICANUS) 

 IN THE FLORIDA EVERGLADES. 



BY THOMAS E. SXYDER. 



On March 25 to 29, 1917, I visited Mr. C. A. Mosier's camp 

 (plate XV, fig. 1) in Royal Palm Hammock, about 48 miles southwest 

 of Miami, Dade County, Florida, to collect termites. On March 

 26, at about 4.45 a.m. (central time) a peculiar buzzing was heard, 

 which increased in volume until it became a dull roar. Mr. 

 Mosier stated that this was caused by a large horsefly (specimens 

 were identified by Mr. C. T. Greene, as Tabanus americanus) 

 and that this buzzing had been going on for 10 days to 2 weeks 

 at about the same hour in the morning, but that it was at its height 

 about 1 week ago and was now waning. The adults were flying 

 in countless thousands. Mr. Mosier did not notice this habit 

 last year and my observations indicated that this species was not 

 especially common last year either at Royal Palm Hammock 

 (Paradise Key) or Miami. 1 



Observations were made on the flight each morning. The 

 flies took to the wing at the "peep of day" when the birds com- 

 mence to sing and a few of the stars are still visible. The buzzing 

 commences gradually but increases very rapidly in volume to a 

 dull roar. The whole flight lasts only about 20 minutes and is at 

 its height for about 15 minutes gradually increasing and subsiding. 

 At sunrise on March 26 about 5.20 the buzzing had been over for 

 some time, the last adults flying at 5.05 and the flies had quieted 

 down and only flew when disturbed. During the flight the 

 gradually increasing buzzing attracts other flies till all are on the 

 wing: the flies can be heard as they leave the tree trunks, where 

 they have been resting and striking the foliage with their wings, 

 as they rise up through the trees. They fly above the tree tops 

 :ind can be observed all over the hammock, the buz/ing is loudest 

 in the main hammock, which is the largest in area. 



Individuals hover in the air in one spot in openings in the forest 

 canopy (where the tree crowns don't overlap ) and over the 



1 Snyder, T. J-:. Horseflies as ;i IVst in Southern Florida." Proc. 

 Ent. Soc. \y : .sli.. Vol. XVIII, No. 4, December, 1916 (June 11, 1917), pp. 

 208-210. 



