OBSERVATIONS ON THE LIFE HISTORY AND HABITS 
OF HYDROMYZA CONFLUENS LOEW., (DIPTERA).* 
By Pau S. WELCH. 
During the past three summers the writer carried on some 
biological investigations in the vicinity of Douglas Lake, Mich., 
in the extreme northern end of the southern peninsula of that 
state. The work was done in connection with the University 
of Michigan Biological Station, the facilities of which aided 
materially in securing the data which form the basis of this 
paper. 
Hydromyza, one of the several small genera belonging to 
the Cordyluride, has only one species (H. confluens Loew) 
reported for North America. This species is northern in its 
distribution and seems to have been reported only from New 
Jersey (Johnson, ’04, p. 162) and Michigan (Needham, ’08, 
p. 270). Needham reported it from Walnut Lake, in south- 
eastern Michigan, and predicted that it would probably be 
found common about Nymphaea beds in the United States. 
In, looking over the literature relating to this insect the writer 
was surprised to discover how little has been written about it. 
Aside from a brief, two-page paper by Needham (’08, pp 270- 
271), nothing seems to have been written on the habits or life 
history of this very interesting insect. It occurred in sufficient 
numbers to make possible the accumulation of a number of 
interesting facts relating to this species. The data presented 
in Needham’s brief paper were tested and found to agree 
with the observations of the writer in almost every respect. 
Data merely mentioned by Needham have been worked out 
in more detail and a number of new observations were made. 
Unfortunately the writer has been unable to observe the 
method of oviposition and the younger larval stages have 
not been studied. 
THE LARVA. 
Food Plant—Hydromyza confluens was found in con- 
nection with the yellow waterlily, Nymphaea americana, 
(Provancher) Miller & Standley. This is the form which has 
until recently been included under the name JN. advena or N. 

* Contribution from the University of Michigan Biological Station, No. 21. 
135 
