OKANGE SWIFT. 
181 
are firy and unadhesivc, and though white when first 
discharged, they soon acquire a black colour which 
malces them exactly resemble grains of gunpowder. 
In some of the species a peculiarity is obsen’-able 
in the structure of the hinder legs. In the male of 
H. Humuli these members are ftlmished with a 
dense tuft of very long hairs which has been con- 
jectured with some appearance of probability to be 
partly the cause of its peculiar undulating flight. 
In the same sex of H. Hectiis, the entire tarsus is 
wanting in the hinder legs, and the tibia is tufted 
in a similar manner. These insects may be distin- 
guished generically by the shortness of the antennae, 
which ore usuallj' granulated (in some cases, how- 
ever, they are slightly serrated), and not so long as 
the thorax, and by the w<mt of palpi and maxillfe. 
Tlie females are usually largest, and dissimilar to 
the male in colour and markings. The latter sex, 
in the species figured, is of a fulvous colour, the 
upper n-ings variegated with chestnut and marked 
with white lines, one of them near the base placed 
obliquely, and forming a right angle with another 
at the interior margin which extends nearly to the 
apex ; there is a small triangular dusky spot on the 
disk. The female is brown, with a whitish patch 
at the base of the upper wings. 
It is found occasionally in many parts of England, 
in the montlis of August and September. 
