42 PAPERS OX INSECTS AFFECTING VEGETABLES. 



After the larvae have crawled between the terminal leaves or mined 

 into any portion of the plant they are beyond the reach of a stomach 

 poison. The period between the hatching of the eggs and the con- 

 cealment of the larva? is so brief that it appears to be a practical 

 impossibility to reach them under field conditions. 



In the light of our present knowledge, the best methods of con- 

 trolling this webworm consist of clean culture, the screening of seed 

 beds, and thorough cultivation. 



The necessity of prompt destruction of crop remnants and the 

 employment of other clean cultural methods can not be too strongly 

 emphasized. It is a disgraceful condition to allow worthless plants 

 to serve as breeding centers for pests which will infest later planting. 



B} T screening the seed beds it is possible to prevent infestation 

 until the time of transplanting. When this method is followed it 

 is advisable to leave a few plants exposed near the screened beds. 

 These exposed plants will attract the moths, and eggs will be de- 

 posited on them. As soon as the eggs have hatched and the work of 

 the larva? becomes apparent these plants should be promptly burned. 



Inasmuch as the larva? of this species pupate in frail cocoons near 

 the surface of the soil, it is possible that thorough cultivation would 

 crush some of the pupa 1 and at the same time induce a more vigorous 

 growth of the plants. 



RECOMMENDATIONS FOR CONTROL. 



While the limited stay on the part of the junior writer in Hawaii 

 did not permit of experiments with other remedies than those which 

 have been considered on previous pages, nevertheless it is believed 

 by the senior writer that in the occurrence of this insect in the 

 southern United States and in California it may be possible to suc- 

 cessfully treat it on cabbage and other cruciferous plants by means 

 of some form of spray, particularly if applied at the outset of at- 

 tack. This point can never be too strongly emphasized, that if we 

 expect to meet with success in combating this as well as so many 

 other insects, work must be begun upon the first appearance of the 

 insects each season, since if the pests can be destro} 7 ed then, it should 

 materially decrease the injury for the entire year. If the first 

 generation is missed, the second and third should be treated. 



It should be stated that Mr. H. M. Simons, Charleston, S. C, one 

 of the first to report this species as a pest in America, found that 

 a mixture of kerosene oil and soap sprayed upon infested plants 

 served as a deterrent against the larva 1 of this moth, but that the 

 larvae returned as soon as the odor of the kerosene had become 

 exhausted. Kerosene-soap emulsion and nicotine solutions and whale- 

 oil soap should be given thorough tests as deterrents and insectides, 

 both alone and mixed with arsenicals. 



