April, '14] FERNALD AND BOURXE: ONION INSECTS 199 



ately good results. The cost of the soap and of its preparation and 

 appHcation came to about $20 an acre for each appHcation, bringing 

 the cost too high to make it a desirable treatment. 



Carbolic acid and lime also failed to give good results. Either the 

 coating around the plants was too thin or the maggots went beneath 

 it. After everj^ cultivation or row weeding it was necessary to repeat 

 the treatment, and the infestation of the treated rows was as great as 

 of the untreated check rows. The cost of the material was not great 

 but the application had to be carefully made in order to obtain a 

 complete crust around the plants, and this took time. The total cost 

 for one application finally figured out at about $23 per acre, which in 

 view of the repetitions necessary after each cultivation would make the 

 cost too great even if it had been effective. 



Kerosene emulsions, one part to nine; to fourteen, and to nineteen 

 of w^ater, were applied like the soap wash and repeated at intervals of 

 ten to fourteen days. The different strengths seemed to give no differ- 

 ence in the results and no injury to the plants or protection from the 

 maggots was found. The total cost for one application per acre varied 

 from about $20 to $24, which for three applications would be too 

 high. 



Carbolic acid emulsion gave the best results so far as protection 

 from maggots was concerned, though not being entirely effective. The 

 cost for the four treatments necessary would come to from $35 to 

 $50. 



The conclusions drawn from these tests were that none of the treat- 

 ments are entirely satisfactory and that most of them are in any case 

 prohibitive because of their expense. Accordingly, the problem may 

 be formulated somewhat as follows : To find some material which will 

 destroy or repel the onion maggot at a total cost of less than $50 per 

 acre. 



The greatest item of expense is, of course, the application of the 

 material, and any method which will reduce this is of value. Each 

 repetition of the application rapidly increases the cost, and if a sub- 

 stance can be found with which a single treatment will be sufficient, 

 this wall be a great advantage. If, then, this treatment can be com- 

 bined with the planting, the extra cost will be mainly that of the 

 material. 



During the past season, therefore, an attempt has been made to 

 discover some repellent which could be fed on to the seed from a supply 

 tank just behind the seed spout and in front of the roller, which would 

 keep the maggots away. 



A number of materials were tested for this purpose, and it was found 

 that some are injurious to the seed, preventing its germination, and 



