26 INSECTS AND MAN 



(/) Lepidoptera (scale wings), butterflies and moths, have 

 four pairs of wings, usually covered with scales and mouths 

 adapted for sucking. 



Of the butterflies, the most important families are the 

 Papilionidce, containing the largest and handsomest species 

 in the world: our swallow-tail butterfly belongs to this 

 family; the Pieridce or cabbage butterflies, of which the 

 destructive "cabbage white" is an example; the Lycce- 

 nidce or "blues," remarkable for the eccentric forms of 

 their larvae, and the " skippers " or Hesperidce, curious in- 

 sects forming a connecting link between the butterflies 

 and moths, of which the best known families are the Sphin- 

 gidce or hawk moths ; the Bombycidce or silkworm moths ; 

 the Noctuidce, usually sombre-coloured moths, and, as a 

 family, exceedingly destructive in the larval stage; the 

 Tineidce, of which the clothes moths are examples ; and the 

 Tortricidce, harmful, in the main, to cultivated plants, the 

 larvae of the majority being leaf rollers. 



(g) Diptera (two wings), house fly, tsetse fly, gnats, etc., 

 provided with two wings only, the second pair being reduced 

 to club-shaped stumps, known as halteres or balancers ; their 

 mouths are piercing or suctorial. 



The flies are the most important order, from the medical 

 standpoint, so many of them are carriers of disease in man 

 or animals. There are two sub-orders, the Orthorrapha and 

 the Cyclorrapha. Some important families of the former 

 order are, the Culicidce or mosquitoes, a cosmopolitan 

 family of blood-suckers ; the Tipulidce or crane flies, with 

 crop-destroying larvae known as "leather jackets"; the 

 Cecidomyidce, minute gall-producing flies, for the most part, 

 and, for the rest, enemies of the husbandman ; Psychodidce 

 or owl midges, of which one species transmits disease ; 

 Chironomidct} or midges, and Simulidce or buffalo gnats, 

 some species of which are looked upon with suspicion, at 

 the present time, by medical entomologists; the Myceto- 

 philidce or fungus gnats, with a predilection for ovipositing 



