16 BULLETIN 875, IT. S. DEPARTMENT OF AGRICULTURE. 



weevils. Then they want to get action immediately and desire to 

 make a hurried purchase of calcium arsenate and dusting machinery 

 to try to save the situation. 



To secure control after the weevils have become excessively nu- 

 merous and have punctured nearly all of the fruit is very difficult 

 and usually involves the use of excessive dosages of poison at short 

 intervals and, furthermore, requires an unusually large number of 

 applications. Consequently the operation is very expensive at. best 

 and is also exceedingly hazardous. A very short delay under such 

 conditions is extremely dangerous. The writers do not advise any- 

 one to start poisoning under such conditions with a view of protect- 

 ing the plants sufficiently to permit the setting of a new crop. 

 Sometimes a certain amount of poisoning under such conditions is 

 extremely profitable, as, for instance, when a fair crop of young 

 bolls has been set but is still in danger of weevil attack, owing to 

 the fact that the bolls have not yet developed beyond the point of 

 injury. When the weevils become excessively abundant in such a 

 crop they quite frequently not only overtake the square formation 

 but also destroy a high percentage of the bolls, and poisoning at this 

 time will often save the bolls which are already present on the plants. 

 Since these bolls require protection for only a very short period, it 

 is possible to make perhaps two applications under such conditions 

 and thus retard the weevils sufficiently to eliminate injury to the 

 bolls. It should be remembered, however, that this is quite a dif- 

 ferent proposition from starting in and attempting to control the 

 weevils to the extent of permitting new squares to develop, bloom, 

 form bolls, and reach maturity. 



EARLIER SEASON TREATMENT OF ISOLATED INFESTATIONS. 



The expense of weevil poisoning can be considerably reduced in 

 many cases by localized treatment of the most heavily infested 

 patches early in the spring. Often only a few acres in a large field 

 will be infested early in the season. These may be distributed along 

 a strip of timber or may adjoin barns, cabins, or other hibernation 

 quarters. The weevils tend strongly to attack the largest plants 

 available on emergence in the spring, and in case of any inequalities 

 of soil fertility such as are very commonly found, it will generally 

 be noted that the weevils will concentrate on the patches of larger 

 cotton. Under any such condition it is often possible greatly to re- 

 duce the infestation of the entire field and to delay considerably the 

 date of general poisoning by going into these isolated spots fairly 

 early in the season and treating them thoroughly before the weevils 

 have an opportunity to spread. 



