5' 



few adults that have emerged in the meantime, and which at the time 

 of the first fumigation were in the late pupal stage, and all the larva; 

 which resulted from the eggs present at the first fumigation. The 

 adults killed by the second fumigation will have deposited a few 

 eggs, the larva; from which will be in the first, second and third in- 

 stars two weeks after the second fumigation, and a third treatment 

 at this time will destroy them. Theoretically the house will now be 

 entirely freed from the pest. The writer's tests indicate that this is 

 possible, but even though it is not actually accomplished, no trouble 

 need be expected from the insect for many weeks. In badly infested 

 houses even a single fumigation will so reduce the numbers of the 

 insect as to prevent furthur injury for at least a month, and an occa- 

 sional fumigation in slightly infested greenhouses will control the 

 pest so as to prevent the possibility of its increasing to an injurious 

 extent. 



Fumigation Combined with Syringing. If for any reason it seems 

 undesirable to use hydrocyanic acid gas, a systematic treatment with 

 a fumigant and a contact insecticide should result in effectually con- 

 trolling the insects. The first step in the process should be to pre- 

 vent, the enormous production of eggs by ridding the house of the 

 adults. For this purpose, Nicoticide is the most effective and cheap- 

 est material, aside from hydrocyanic acid gas, which was used in the 

 foregoing experiments. Other similar preparations may be found to 

 be equally good for the purpose. For each two thousand cubic feet 

 of space from one to two ounces of Nicoticide should be used, ac- 

 cording to the tightness of the house. This fumigation should last 

 all one night, and be followed the next day by a thorough syringing 

 of the plants with a contact insecticide, the most desirable used by 

 the writer being P>owker's Tree Soap, at the rate of one ounce in a 

 gallon of water. One such combined treatment should so reduce the 

 numbers of Aleyrodes in a greenhouse that further treatment would 

 be unnecessary for several weeks. If it is desired to continue this 

 treatment further, the house should be fumigated as before, one week 

 after and then sprayed as before, two weeks after the first treatment. 



