156 THE ENTOMOLOGIST. 



raonly observed, than the female ; occasionally it is found in 

 swarms. Kolenati captured forty-two specimens in the Neva, 

 all males ; Nolcken went to the same locality, and look 

 something like 150, again all males. Zeller had it in num- 

 bers from Pomerania, but only of the male sex. Hagen had 

 seen it in numbers, but could not remember a single female 

 taken in Prussia. Dale, in the last letter I had from him 

 (within three months of his death, when the veteran entomo- 

 logist was over eighty), wrote ' the males were in great 

 abundance, the females very rare.' Brown, in a recent letter, 

 writes 'I have seen, I should almost say, hundreds of males 

 on the wing at a time.' Ritsema took fifty specimens near 

 Haarlem, all males. 



" Unless disturbed, they are inactive by day, but fly 

 briskly jn the evening over the surface of water. Kolenati 

 found them sitting sluggishly on the Potamogeton, close to 

 the water, the majority on the flowers and young seeds; 

 when active, they ran on the surface of the water. According 

 to Dale, ' they flew nearly on the surface of the water, 

 sporting about in various directions.' Brown found them 

 quietly sitting on leaves, or other objects which protruded 

 from the stream, whilst others flew slowly, or, as he elsewhere 

 expressed it, were 'skipping over the surface' of the Trent. 

 Reutti's observation is, that the male flies always close to and 

 on the water, by day only involuntarily, but by night briskly. 

 M'Lachlan records that between 8 and 9 p.m., in June, 

 ' they began flying rather rapidly over the surface of the 

 water, and close to it, occasionally coming on to the wet 

 mud.' Knaggs mentions that ' it skims along the surface of 

 the water,' but although the usual habit is to fly close to the 

 water, he has 'occasionally seen it mount perpendicularly 

 into the air, rising higher and higher, until lost to sight.' 

 M'Lachlan tells me that he too saw the male thus mount into 

 the air, but only when caught by a current of wind, so that it 

 was an involuntary act. Boyd tells me that he observed the 

 females to fly, as a rule, at a greater height above the water 

 than the males. Nolcken found them, either sitting drowsily 

 on floating pieces of Potamogeton or other objects, often two 

 or three so close together that at first he thought they were 

 in coilti, or fluttering about in small circles close to the 

 surface, then raising themselves a few inches above it, but 



