60 Vict. 



Provincial Board of Horticulture. 



47 



Fig. 1. 



Natural size. Fig. 2. 



SYRPHUS FLIES. 



Natural size. 

 Sp. unnamed. 



Fig. 3. 



In the above cuts Fig. 1 represents the fly ; Fig. 2, magnified, the case in which 

 it transforms into a fly, and Fig. 3, magnified, the larva. 



The Syrphus Flies are also great destroyers of aphides. The larvae feed entirely upon 

 aphides, and appear and disappear as the aphides appear and disappear. The larva is a foot- 

 less, eyeless, flattened, transversely wrinkled, gaily coloured, green and purple 

 Syrphus Flies, maggot, having a very extensile body, which enables it to reach up and grasp 

 the aphis with its peculiar looking mouth. The single egg, deposited in a 

 group of aphides, hatches forty-eight hours after it is laid, and the larva becomes full-grown 

 and transformed into a pupa in five or six days. The reason of this extremely rapid develop- 

 ment in the first two stages, the egg and the larva, is explained when we consider how brief is 

 the existence of the aphis, and how suddenly its colonies appear and disappear. When the 

 larva is actively feeding it destroys dozens of aphides, one after the other, and its body changes 

 colour. When filled to repletion the larva falls into a lethargy, lasting two or three hours, 

 during which the process of digestion changes the juices of the body to varying shades of brown. 

 After the process of digestion has taken place, the larva again begins its work devouring 

 aphides. 



DEVIL'S HORSE or WHEEL BUG (Prionidus cristatus. Linn.) 



This insect feeds upon scales and aphides and destroys large numbers of caterpillars. The 

 female deposits her eggs in a hexagonal mass on the leaves and bark of trees, on fence rails, 

 etc. Generally, there are about seventy eggs in a bunch. The young are 

 Wheel Bug. blood-red in colour, with black marks, and resemble the adult only in form 

 and habits. These insects. prey upon pests by inserting into them their pro- 

 boscis, which injects a most powerful, poisonous liquid into the wound. The victim thus pierced 

 dies in a very short time. They then leisurely suck the juice out. The perfect insect is of a 

 gray colour and has a high, semicircular ridge or projection on the crest of its throat. 



