DlPTERA 269 



The pear -midge {Diplosis pyrivord) lays eggs in the 

 flower-buds of the pear. The larvK, which are only about 

 5 mm. long when full grown, live a number together in the 

 core of the growing fruit. They leap when disturbed like 

 cheese-maggots, clasping the head with the tail and then 

 suddenly extending the body. About midsummer the 

 dwarfed pears fall to the ground, and if opened the grubs 

 are found in cavities within. When the pears crack the grubs 

 enter the earth, form cocoons and rest till spring, when they 

 pupate and turn to flies. 



Among the other families of Nemocera are the Chirono- 

 midae, to which the harlequin-fly belongs (see Lesson 23), the 

 Culicidse, or gnats (see Lesson 25), and the Tipulidse, to 

 which the crane-fly (see Lesson 26) belongs. 



Sub-order II. — Brachycera 



Antenna neither truly Nemoceran nor truly Athericeran ; if 

 beaded, it always has the joints of various lengths, and generally 

 fewer than in Nemocera ; if it takes the plate-and-bristle form, 

 the bristle is terminal, or else the third joint is segmented. The 

 palps have never more than two, joints. The larval skin is cast 

 at pupation, or retained as a defence for the pupa ; it splits 

 longitudinally and often transversely as well. 



To the Brachycera belong Stratiomys, with its curious 

 aquatic larva (star-tailed maggot), the Tabanidas (popularly 

 named cleggs, horse-flies, and gad-flies) which draw blood by 

 the lancets of the proboscis, which is usually prolonged; 

 as in gnats, it is only the female that draws blood. The 

 robber-flies {Asilidci) superficially resemble hairy bees. They 

 kill and suck insects of all kinds, while the larvae prey upon 

 other insect larvae. The large family of Empidae includes 

 'many predatory forms which pierce and suck flies ; some are 

 very commonly seen hovering over water. 



Sub-order III.^ — Athericera 



Antenna of the plate-and-bristle form, with three basal 

 joints, the bristle springing from the base of the third joint. 

 The palps have never more than two joints. The larval skin 

 is retained during the pupal stage, and cracks transversely to 

 allow the fly to escape, 

 o 



