i86 HEMIPTERA 



The Gad Flies (Tabanida) are most objectionable on account 

 of their biting habits, settling upon horses and cattle and suck- 

 ing their blood. The mouth is armed with a sharp, lancet-like 

 piercing organ, which inflicts a very painful and often dangerous 

 wound, for these insects are undoubtedly responsible for the dis- 

 tribution of various cattle diseases, including anthrax. 



Turning from those Diptera which are transmitting agents of 

 disease to man and domestic animals, to those which ravage the 

 crops, we find them to be quite as numerous. The Hessian Fly, 

 and the Wheat Midge, or " Red Maggot," in the larval stage cause 

 serious injury to wheat. Whole acres of grass-land and corn are 

 destroyed annually by the larvae of the Crane Fly, or "Daddy 

 Long-legs" (Tipula), which burrow into the soil and attack the 

 roots. These brownish-grey-coloured, cylindrical-bodied larvae are 

 popularly called "Leather- jackets," on account of their tough skins, 

 and measure about ij inches in length when full grown. They 

 also attack the roots of garden crops, such as cabbage and lettuce, 

 causing considerable injury and loss. The Cabbage Fly, the 

 Onion Fly, the Carrot Fly, and the Celery Fly, as their popular 

 names denote, are all destructive to various crops. 



The Hover Flies, or Breeze Flies (Syrphida), are a large and 

 important group of handsome insects. They delight in warm, 

 sunny weather, when they may be seen hovering and darting from 

 flower to flower. In the genus Syrphus, which is typical of this 

 group, the female deposits her eggs on leaves that are infested 

 with aphides or plant lice, and the larvas, on emerging, at once 

 begin to devour the aphides, and destroy large numbers of them. 

 In this way they do good service, and are among the few Diptera 

 that can be said to be useful to mankind. 



The Hemiptera are a very interesting Order of insects, which 

 includes the Aphides or Plant Lice, the Bugs, the Lantern Flies, 

 Cicadas, Water Scorpions, and Scale Insects. The Hemiptera are 

 divided into two well-defined sub-orders : (i) the Homoptera, 

 which includes the Cicadas, Aphides, Lantern Flies, and Scale 

 Insects ; and (2) the Heteroptera, or Bugs, Water Scorpions, etc. 

 All undergo an incomplete metamorphosis, that is to say there is 

 only a very slight difference between the larva, pupa, and perfect 

 insect. The larva, which more or less resembles the perfect 

 insect, casts its skin a number of times. After one of these moults, 



