328 PREVENTIVE AND REMEDIAL MEASURES 



was not correctly used. R. J. Smith (1911) has demonstrated, 

 and it has been subsequently confirmed, that if sweet milk is 

 added to the formalin it proves very attractive to flies and the 

 mixture makes an excellent and fatal bait. The solution is made 

 as follows : one ounce or two tablespoonfuls of forty per cent, 

 formalin is mixed with sixteen ounces, that is, one pint of equal 

 parts of milk and water. If this mixture is exposed in shallow 

 plates in the middle of each of which a piece of bread is placed 

 for the flies to alight upon, the flies will be attracted to the 

 solution and poisoned. The formalin has also the advantage of 

 being a disinfectant. Houston (1913) has used the following 

 method of application in the jail kitchen at Rajkot, India, with 

 great success. Instead of exposing the mixture in shallow plates 

 it is sprinkled about the room in tiny pools of one quarter to one 

 inch in diameter from which pools the flies readily drink it. The 

 substitution of buttermilk for the ordinary milk has also been 

 suggested. 



Berlese (1913) has for two years carried out observations and 

 experiments on the control of flies at S. Vincenzo (Pisa) by means 

 of poisoned baits, deriving the idea from his work on the control 

 of the olive fruit-fly by means of sweetened arsenical solutions. 

 He rightly emphasizes the importance of destroying the flies 

 outside the houses and near the breeding places where they con- 

 gregate. He sprayed plants in the gardens and orchards near 

 dwellings, and also heaps of manure and other likely breeding 

 places with the following mixture : 10 parts of treacle, 2 parts of 

 arsenite of potash or soda and 100 parts of water. The operation 

 was performed every ten days and repeated after rain, and the 

 manure heaps were sprayed when a fresh surface was exposed. 

 In 1912 he experimented with small bunches of straw suspended 

 for protection from the weather under conical zinc covers. The 

 straw was dipped in the following mixture : honey, 1 part ; 

 treacle, 1 part ; sodium arsenite, | part ; water, 10 parts. These 

 baits were hung round the houses in such places as the porches 

 and verandas. Berlese states that by the use of these methods 

 he succeeded in totally destroying the flies in each of the two 

 years during the period of his residence in the village. By the 

 perfection of this method, which enabled him to enjoy a flyless 



