3022 



THE JOINTED ANIMALS 



does not sting, they become restless, tossing their heads, and lashing with their 

 tails, but the ' coachman ' may rest on any part of them for any length of time, 

 and never be interfered with, or driven off. ' ' 



The flies of the family Asilidce are generally of a somewhat 

 es> slender build, the body being long and parallel sided, while the legs 

 and wings are long and strong. All are provided with a short, power- 

 ful, piercing proboscis, and prey upon insects of various kinds, often seizing and 

 carrying off butterflies, much larger than themselves. The general form of the 

 members of this family is shown in Fig. i of the annexed illustration, representing 

 Diodria oelandica, a species from the island of Oeland, off the coast of Sweden, with 

 a shining black body, and wings of the same color. Many species of the genus 

 Asilus are found in Britain, but the largest and handsomest of all is the hornet 

 robber fly {A. crabroniformis) , measuring upward of an inch in length, and of a 

 yellowish color variegated with black, there being four stripes of the latter color 

 upon the thorax, and a broad transverse band across the base of the abdomen. 

 Some of the tropical members of the family are far larger, those belonging to the 

 genus My das from South America, being scarcely surpassed in dimensions by any 

 member of the order. The fly represented in Fig. 2 of the illustration is the tessellated 

 empis {Empis tessellata) , belonging to the family Empidce, the species of which 



are predaceous like the Asilidce, 

 and resemble them in form, but 

 differ in certain structural details 

 which need not be dwelt upon. 

 The tessellated empis the 

 largest member of the group 

 found in Britain is ashy gray 

 in color, and has its abdomen 

 ornamented with a chessboard 

 pattern. As Dallas expressed 

 it, " when paired, the females of 

 this and of many other of the larger species of the family are always found to 

 be busily engaged in sucking out the juices of some other insect. It seems 

 probable that the male seizes the opportunity of his intended partner being thus 

 occupied to make his advances; if her mouth were free he would in all likelihood 

 himself fall a sacrifice to her voracity." 



The families of short-horned, straight-seamed flies hitherto consid- 

 ered resemble each other in the fact that the larvae live in the earth, 

 and feed upon the roots of grass or other vegetable matter, while the adults prey 

 upon other animals, whose blood they suck. But in the bee flies (Bomby Hides} 

 so called from the likeness in hairiness and shape they present to bumblebees 

 the larvae, so far as known, live parasitically on other insects, attacking grasshop- 

 pers, caterpillars, etc., while the adults suck the juices of flowers. The genus 

 Bombylius is represented in England by a small number of species, although in the 

 tropics there are large numbers of forms. In all the thick, fat body is covered with 

 long yellow hairs. The wings are powerful; and the head is furnished with a long 



ROBBER FLIES. 

 I. Dioctria oelandica; 2. Empis tessellata. (Natural size.) 



Bee Flies 



