556 Bulletin 78. 



these maggots were seen at any time later in the season." This year he re- 

 ports similar results from a similar use of kainit in the same locality {Insect 

 Life, vii, 196). It is to be regretted that Prof. Smith could not have made 

 these experiments more conclusive by his personal supervision. The de- 

 struction of all of the plants that showed any signs of infection before the 

 kainit was applied, prevents very definite conclusions from being drawn as 

 to the destructiveness of the kainit. In his report for 1893, P- 44i. Prof. 

 Smith mentions that some experiments were made on a fly larva which was 

 at first mistaken for the Onion Maggot. Rewrites us that " this Ortalid 

 larva was remarkably resistant to almost anything that I could use, except 

 the kerosene " ; recently {Insect Life, vi. p. 96) he intimated that kainit was 

 one of the substances used on these maggots which were found in diseased 

 onions and which are so closely allied to the Onion Maggot as to have been 

 mistaken for it. 



It is also worthy of note in this connection that in one of the first references 

 we find to the use of kainit against this pest {Rural New Yorker for 1887, p. 

 238), a Georgian contributor says it must be put on in time to kill the eggs, 

 for it will have no effect on the maggots after they hatch. From the above 

 evidence, we do not feel warranted in recommending that gardeners may 

 expect to kill the root maggots by an application of kainit that would not at the 

 same time kill the plant. 



We are supported in this opinion by the following experiments, conducted 

 on maggots brought here from Long Island. Several thrifty cabbage plants 

 were potted out, and on May 23 some of the soil was removed from around 

 the base of the plants and 100 maggots, none of them over % grown, were 

 placed close to the base and covered with earth. They were left undisturbed 

 until the next day when it was found they had established themselves on the 

 plants. May 24, the soil was removed until at least 25 of the maggots were 

 laid bare. Then 4 ounces of a solution of kainit {Yz lb. to a gallon of water) 

 was poured around the stem ; in one case 20 of the maggots floated about in 

 the solution for over a minute. Another similar cage with ico small maggots 

 was started May 25, and the same amount of kainit applied on the 26th. 

 One of the cages was examined May 25, and the notes say : " No indications 

 that even the smallest maggots have been killed." By June 6, when all of 

 the cages were carefully examined, most of the maggots had changed to 

 pupae. In the cage where the maggots were mentioned as floating in the 

 kainit solution, 83 live pupae were found ; in the other two treated cages 

 there were 50 and 63 live pupae, respectively. An examination of two check 

 cages started at the same time in a similar manner with 100 small maggots, 

 but not treated with kainit, revealed 95 live pupae in one and 71 in the other. 

 If the kainit used at the rate of >^ lb. to i gallon of water is not more effec- 

 tive on the maggots under these somewhat confined conditions than these 

 results show, one surely could not advise gardeners to use it with the expec- 

 tation of killing the maggots. 



To test astronger solution, we started two similar cages of 100 small mag- 

 gots on May 24. May 25, 4 ounces of a solution of the kainit (i lb. to i gal.) 



