16 



crop and attacks it earh' in spring, when, unless the natural enemies 

 come to the fore, it niultiplies in great abundance. In the writers 

 experience the lad3'birds and other enemies soon gain the ascendancy 

 and become so abundant that the}^ are forced to migrate for food. 

 The trap crop will ordinarih^ remain in condition to sustain aphides 

 and their enemies until melons or other crops susceptible to melon- 

 aphis damage have past the danger stage and are ripening. 



The farmer may exercise his own judgment in regard to the loca- 

 tion of the trap crop. The writer believes that the greatest advantage 

 would accrue from planting three or more rows of rape or kale on 

 each side and, in the case of lields of more than 4 or 5 acres, bv plant- 

 ing additional rows between. Planted on all sides, the trap crop will 

 attract aphides and their enemies from every direction, and this result 

 will be facilitated b}^ permitting the growth of weeds between the 

 rows. In fact, weeds are a desideratum in these operations, since 

 they furnish the best natural hibernating places for the lad3^birds and 

 similar beneficial insects. It is advisable also to place boards, loose 

 bark, or hollow logs about the margins of the fields to secure better 

 facilities for hibernation. As fast as one crop of rape, or whatever 

 is used, matures, or its growth is stopt by the aphides (as might 

 sometimes happen), another planting should be made so as to keep a 

 constant suppl}^ of cabbage aphides on hand that the natural enemies 

 may not migrate to other quarters. 



COXCLUSIOX. 



Many of the remedies that have been indicated as of service in the 

 control .of the melon aphis (with the exception of the last) operate 

 against most other cucurbit insects, several species of which are 

 usually present. Thus the kerosene emulsion and soap solutions kill 

 young squash bugs and act as deterrents to most other insects, and 

 bisulfid of carbon will kill other soft-bodied insects besides the aphides, 

 while fall plowing and clean cultural methods are valuable in destroy- 

 ing the squash-vine borer. Tobacco fumigation, however, has little 

 effect on these other insects as they occur in the fiekL 



Approved: 



James Wilson, 



Secretary of Agriculture^ 



Washington, D. C, Novemher IJ^, 1906. 



O 



