24 



had been introduced after the top layer was treated. There 

 was therefore reasonable ground to believe that the beetles 

 laid eggs on the treated seeds as being the first they met with. 

 In a subsequent experiment a quantity of infested seeds was 

 placed at the bottom of the pot, uninfested seed about four 

 times the quantity was placed on top of it and then the layer 

 of oiled seeds was introduced. In spite of it, the results were the 

 same. It appeared, therefore, certain that in this experiment 

 too, beetles had sought the top surface for egg laying even 

 though they must have emerged far below the surface. It 

 was this fact coupled with the observation that the percent- 

 age of infested seeds diminished directly with their depth 

 from the surface that established beyond a doubt 

 the instinct of the beetles to seek always the top 

 surface. 



Once the discovery was made, the wisdom of some of the 

 methods adopted by the raiyats became clear at once. The 

 bamboo bin with a narrow neck and a hole at the side ap- 

 peared admirably suited to prevent serious damage by the 

 beetles ; for, in this arrangement, the top surface is very nmch 

 reduced and is left undisturbed. In the " moodais " there 

 is no level surface on top at all and the seeds are packed so close 

 together that there is little space afforded to the beetles to 

 proceed far from the place of emergence to find a male or to 

 lay their eggs. When the seeds are mixed with husk in these, 

 the interspaces between the seeds are still further reduced. 

 The practice of keeping these '' moodais," bags, etc., one on 

 top of another is also to be recommended as the pressure so 

 exerted tends to reduce further the space between the seeds, 

 required by the beetles and hinder their multiplication. 

 With regard to oiling the top layer of seeds, the method, 

 though effective, does not entirely prevent beetles from 

 getting into the untreated layer below and laying their eggs 

 on the seeds there. 



Another method that deserves notice is the storage of 

 pulses under ragi {Eleusine coracana) or savai {Panicum. fni- 

 mentaceum). These grains are not attacked by pulse beetles. 

 When they are used as a top layer several inches deep, the 

 beetles, on emergence to the surface, do not generally get 

 back to the pulses below and the latter are usually saved 

 from attack. 



There can be no question that these methods reduce 

 damage to a great extent. At the same time, without consi- 

 derable care, the few that manage to emerge may success- 

 fully reproduce and there is the chance of injury extending to 



