266 ANIMAL LIFE 



organised economy of their simpler allies is made 

 known. 



Amongst these less impressive forms are the 

 saw-flies, gall-flics, and ichneumon-flies. The saw-flies 

 are easily distinguished by the absence of a ' waist,' 

 and the possession, in the case of the abundant female, 

 of a sting-like organ consisting of two remarkable saws 

 and their supports. By the aid of this apparatus the 

 mother fly is able to cut passages into the leaves, stems, 

 or trunks of plants before depositing her eggs therein. 

 The gall-flies are minute, pitchy-black, thin-waisted 

 insects which may be identified by their straight 

 antenna; . The ichneumons are thin-waisted and often 

 brilliantly coloured insects, the mothers bearing a 

 usually long sting-like weapon for depositing their eggs 

 in or upon the bodies of caterpillars. 



Sau ] -/Jics. — The saw-flies of the rose, gooseberry, 

 currant, and turnip do an immense amount of mischief 

 in this country, and abroad, where the conditions are 

 more favourable, their ravages are correspondingly 

 severer. The gooseberry fly lays its greenish eggs 

 along the mid-rib of the leaves, and from them there 

 issue in a week minute white larva; with twenty legs 

 and sucker-like feet. At the first moult they assume 

 a green colour spotted with black, and in many ways 

 resemble true caterpillars, as, for instance, in colouring 

 and attitude and in the possession of prolegs. After 

 feeding for a month they become yellow in tint, creep 

 down to earth and pupate, or may hibernate and 

 pupate in the following spring. 



