February, '17] METCALF: lime as an INSECTICIDE 75 



I think that this was due to the fact that all stages of these weevils 

 are to be found in the peas at one and the same time, and while this 

 strength of carbon bisulphide is ample to kill the adults that have 

 emerged from the cow peas it does not have any effect on the stages 

 in the pea nor on the eggs which are glued to the outside of the pea. 

 Hence the following year we went a little farther afield and tried, not 

 only the carbon bisulphide at fifteen and thirty pounds per 1,000 

 cubic feet of air space, but also tried mixing peas with kerosene at the 

 rate of one-half and one pint per bushel, crude carbolic acid at the 

 same strengths, and air slaked lime at the rate of one part to four parts 

 of peas and at the rate of one part to eight parts of peas. These peas 

 were treated late in September, 1913, and left until the following 

 spring when it was found upon examination that the peas treated 

 with air slaked lime one to four gave a germination of 71 per cent, 

 the peas treated with air slaked lime one to eight a germination of 

 48 per cent; whereas, the peas treated with carbolic acid gave only 

 21 per cent, those with kerosene 21.5 per cent, and those with carbon 

 bisulphide 17.5 per cent. This led us to believe that air slaked lime 

 was perhaps the most effective remedy that we could use against the 

 cow-pea weevils. 



In December, 1915, we planned a somewhat more elaborate experi- 

 ment in which peas were treated with varying proportions of air 

 slaked lime ranging from four parts lime to one part peas to one part 

 lime to eleven parts peas. These peas were moderately infested at the 

 time they were treated, the variety called general crop in the table 

 being the worst in this respect. Unfortunately, no germination tests 

 were made at that time; neither were there any tests made at the 

 usual planting time, — two critical points that were overlooked. How- 

 ever, treated peas were stored in ordinary sacks in the seed room and 

 tied to each sack was a liberal sample of untreated peas which served 

 as a check. These peas were examined this past fall, and two checks 

 were taken upon the effectiveness of the various strengths of lime tried. 



One check consisted of counting 1,000 each of the treated and check 

 peas and then counting the number of adult emergence holes per pea. 

 The number of adults emerging from a single pea ranged from none to 

 twelve with a mean of 1.04 for the treated peas and a mean of 3.4 for 

 the untreated. However, the mean of the four greatest strengths 

 tried was .027 for the treated peas and 3.52 for the untreated peas. 

 This is, perhaps, not altogether a fair test of the effectiveness of a 

 remed}^ for it is rather hard to believe that the lime could have any 

 effect on the adults ready to emerge. On the other hand, larvae that 

 are able to pupate and then die have caused as much damage to the 

 peas as have larvae which pass through their transformations and 



