864 AN INTRODUCTION TO ENTOMOLOGY 



flies; to protect the plants when they are set out by fittinj^ around the 

 stem of each next to the ground a tarred paper card, these cards can 

 be obtained from seedsmen and dealers in garden supplies; and by 

 the use of a solution of corrosive sublimate crystals, one ounce dis 

 solved in ten gallons of water. Two applications of one-half cupful 

 to a plant are made, one, three or four daj'S after the plants are set, 

 and another eight or ten days later. The solution is poured on the 

 stem and at the base of the plant. Great care should be taken to 

 keep the supply of this poison where children or animals can not 

 get it. 



The onion maggot, /fy^mj^m antlqua.- — -The larva of this species is 

 often exceedingly destructive to onions, destroying young plants in 

 the spring, and when the plants are older, burrowing into the bulb 

 and causing decay. This species is difficult to control. As the flies 

 require from ten days to two weeks after emergence in which to 

 matiu-e their eggs, many of them can be destroyed before they are 

 ready to oviposit by a poisoned bait spray composed of one-fifth ounce 

 sodium arsenite, one pint molasses, and one gallon water. There are 

 two or three generations annually of this pest. 



The raspberry-cane maggot, Hylemyia ruhlvora. — The larva of 

 this species burrows in the new canes of black and red raspberries and 

 blackberries and kills them. The eggs are laid on the young shoots in 

 the spring. The larva bores into the pith of the shoot, and tunnels 

 downward; when about half way to the groimd it girdles the wood 

 beneath the bark. The part of the shoot above the girdle soon wilts, 

 shrinks in size and droops over. The larva continues its burrow 

 downward in the pith to the surface of the ground, transforms to a 

 pupa without leaving its burrow in late June or early July; but the 

 adult does not emerge till the following April. To check the ravages 

 of this pest, cut off and bum the wilting canes as soon as observed. 



The beet or spinach leaf-miner, Pegomyia hyoscyami. — This leaf 

 miner infests the leaves of beets, sugar-beets, spinach, orach, mangels, 

 and chard. The mine at first is thread-like but is soon enlarged to 

 form a blotch. Several larvae usually occupy the same leaf and their 

 mines usually coalesce. There are several generations each year, and 

 the winter is passed in the pupal state under fallen leaves in the soil. 

 Where practicable the infested leaves should be picked and burned. 

 By plowing the field deeply as soon as the crop is removed the over- 

 wintering pupae can be buried . 



The kelp-flies, Fucellia. — The larvae of these flies live in brown 

 sea-weeds, cast up by waves along ocean beaches. The adults can be 

 found all siimmer long on the masses of these weeds often in immense 

 numbers. The North American species, of which thirteen are known, 

 were monographed by Aldrich ('i8). 



Family GASTROPHILID^ 

 The Bot-flies of Horses 

 This family includes the well-known pests the larvas of which 

 infest the alimentary canal of horses and which are commonly known 



