310 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



against the Aveevil that will be adapted to the very different sets of 

 conditions existing in the various cotton districts of the coast region. 

 The variety of conditions that obtain in the different districts has 

 already been dwelt upon, and it is evident that specific recommenda- 

 tions must be made for each set of conditions. The following general 

 lines of cultural control work should be tried out under var\dng condi- 

 tions, with different varieties of the cotton plant : — 



(1) Plant the cotton far enough apart so that the sun may strike 

 the ground between the plants during the more humid season of the 

 year, at this time keeping the fields clean of weeds and grass and 

 pruning out enough of the branches in large plants to prevent shading 

 of the ground. This will allow the hot sun to dry up the fallen squares 

 containing the early stages of the weevil, thus killing the latter. 



(2) Irrigate during the dr}- season and allow as much shading of 

 the ground by the plants and w^eeds as possible during that season, 

 in order to increase the humidity in the fields. While the result will 

 be a certain amount of increased activity on the part of the weevil, 

 what is more important the parasites and enemies of the weevil will 

 remain largely active through the dry season and in that case will 

 probably gain on the weevil from year to j'ear until they dominate it. 

 The parasites appear to develop in a somewhat shorter time than does 

 the weevil, and it is probable that they do not persist through the dry 

 season as readily nor in as large proportion as does the weevil. It 

 seems thus indicated that they largely lose in the dry season the ground 

 gained during the humid season, which would explain their present 

 inability to catch up with the weevil in point of numbers. This ap- 

 plies to districts like Piura Department which have a pronounced dry 

 season. Rearing experiments covering the Piura and Chira cotton 

 districts have shown that the parasites and weevils to develop in the 

 squares and newly-set bolls during July and August at the rate of 

 one parasite to about five weevils. As these parasites are all native 

 species and have undoubtedly been at work on the weevil in Piura 

 Department for very many years, perhaps centuries, it is clear that 



• they will never catch up with the weevil there under present condi- 



♦ tions. It is very probable, however, that they may be aided to the 

 point of greatly increasing their efficiency. 



(3) Cut the cotton plants back every year, or replant every year, 

 the replanting or cutting back to be done as nearly as possible at 

 such season as to bring the bulk of the production of green squares 

 on the plants at the dryest season of the year. This may perhaps 

 be done in certain districts with some varieties of cotton. In those 

 districts having a very dry season it would prevent damage by the 

 w^eevil by allowing the buds and flowers to form while the weevil is 



