FAM. EMPIDID/E 7 
above the lower protuberances. In the aquatic Hemerodromias the terminal spiracles are replaced by 
a bunch of delicate external tracheze. 
The pupa are free, not encased in the last larval skin. The head bears two small carinated 
setigerous tubercles on the upper anterior part; antennal sheaths raised above the level of the face, 
directed downward and slightly outward and tapering apically; proboscis elongated. The thorax is 
generally furnished with long bristles but not with thorns. The respiratory organ may consist of short 
stalks (Rhamphomyia) or be greatly elongated (Drafetis). .Prothoracic spiracles are present. The hind 
tarsi extend much beyond the wings. The abdomen may be provided above with girdles of small teeth 
alternating with bristles and ventrally with hairs alone, or may have a dense dorsal covering of small 
spinules. Seven pairs of abdominal spiracles are present. In Hemerodromia eight pairs of very long 
filiform tracheal tubes extend from the position of the spiracles. 
Ethology and Occurrence. — Empidide are especially abundant in the spring and early 
summer in the undergrowth of shady woods. They are prone to occur in mountainous districts and in 
rather humid regions. While such is the general distribution several of the genera have adopted 
specialized habitats. For example, most of the Clinoceratinz frequent running water, some resting 
beside waterfalls or on water-splashed rocks in swift streams or even amphibiously entering the water; 
species of the Hemerodromiina are to be found in the shady foliage overhanging the banks of 
streams; Tachyfesa stalks over the trunks of smooth-barked trees; Tachydromia nimbly runs over rocks 
in search of its minute prey ; Platyfalbus occurs in the summer and is pratal; while Chersodromia and its 
allies are dwellers of the sea shore and as a consequence of strong sea breezes are loath to take to the 
wing, in some instances having the wings abortive. In dry regions Empididz are rare, having given 
place to their more powerful predatory relatives, the Asilidze. Asa group the Empididz are boreal, 
though this impression may be the result of the large number of species recorded from the mountainous 
regions of Europe and North America. Species occur in the tropics, notably the yellow-bodied 
Drapetis and Syneches, and a not inconsiderable number are known from the southern hemisphere. The 
small size, soft consistency and usual lack of distinction make the Empididz less desirable objects of 
collection than the more striking exotic species, which may explain why some regions have produced a 
meager Empid fauna to date. 
Feeding Habits. — Most adult Empidide are predatory on small insects, notably the 
Diptera, the proboscis being developed for piercing the bodies of their victims. To assist in the capture 
of prey one or the other pairs of legs are sometimes modified into raptorial organs fitted with holding 
spines. Various insects are caught for their body-juices, but principally Diptera are selected. The 
larger species of Empis prefer the Bibios, the smaller species of Emis procure Cecidomyias. The 
prey of Hybosis usually hymenopterous. Many Empididz are cannibalistic, feeding either on smaller 
related forms or even on members of their own species. An interesting way of procuring a miscel- 
laneous lot of insects is to imprison a swarm of dance-flies in the net and sort over the victims dropped 
bythe Empids. Borboride, Chironomide, Blepharoceride, Bibionide, Psychodide, 
other Empidide, etc., sometimes rare species, are in the haul, and nearly always not having been 
crushed by their captors are in good taxonomic condition. ; 
Many Empididz frequent flowers. Of the Anthophilous species, some, like AzAhalia, have a 
soft proboscis and perhaps are dependent on nectar, while others, like Emfis or Drafetis, use their 
mouthparts also for the capture of insect prey. 
Ansemotropism. — Because of the strange habit of some species of RAamfhomyia, Empis and 
Hilara ot hovering and zig-zagging in the air in swarms, the family designation of Dance-flies has 
