FIELD NOTES ON TABANUS N1GBO- 
V1TTATUS MACQUART 1 
By N. S. Bailey 
Cambridge, Mass. 
This horsefly was the subject of an intensive study that 
was started in mid-Julv, 1946, and was suspended only 
with the advent of winter. The fly might well be called 
the Saltmarsh Greenhead since its immature stages are 
evidently quite dependent on the conditions of the Spar- 
tina zones for their development. Wherever expansive 
salt marshes occur — from Nova Scotia to Texas — this 
insect is known and may become locally abundant. At 
such times it is extremely annoying to man and to do- 
mestic animals. Despite its general coastal distribution 
and common occurrence, the literature records only 
meagre details of its life history or of its specific require- 
ments. This paper reports some initial results of the 
current investigation. 
Abundance. Two incidents will serve to emphasize 
how abundant the species is at the height of its season. 
In Essex County, Massachusetts they appear about the 
first of July each year and are at their peak for the last 
three weeks of that month. Usually there is a marked 
decline in their numbers by early August. The decline 
is augmented when a northeast storm brings a spell of 
unseasonably cold, wet weather. The past summer was 
typical in this respect. 
My real introduction to this species came on the warm, 
sunny afternoon of July fifteenth. A call was made at 
the farm of Mr. Martin Burns on U. S. Route 1 in New- 
bury. He was found mowing a field that lies above and 
just south of the Parker River. Two sturdy grey horses 
1 This investigation of the biology of T. nigrovittatus is being conducted 
for a joint board of the State Department of Public Health and the State 
Reclamation Board with a grant from the Massachusetts Legislature. I 
wish to acknowledge the generosity of Dr. Joseph C. Bequaert, Curator of 
Insects in the Museum of Comparative Zoology, who freely devoted his time 
to the determination of the Tabanidae and liberally assisted me in many other 
ways. For the progress of this study I am greatly indebted to his friendly 
guidance. 
62 
