12 METHODS OF CONTROLLING TOBACCO INSECTS. 



which condition they are most susceptible to changes in temperature 

 and to other climatological changes. 



A week or ten days should elapse between the time of cutting the 

 tobacco and the plowing of the land, in order to give all larvae that 

 are in the soil time to change to the more helpless pupal stage. Plow- 

 ing should be done as soon thereafter as possible, so that the pupa? 

 will be exposed as long as possible to unfavorable conditions. 



It is the practice in many localities of Kentucky and Tennessee to 

 disk the land that has been in tobacco in preparation for the wheat 

 that is usually sowed after the tobacco crop has been harvested. In 

 some localities it is thought that disking tobacco land is a better 

 preparation than plowing, for the reason that plowing loosens up 

 the soil too deeply and thatthe wheat will freeze out more easily. 

 Undoubtedly this may be true for some soils, that is, soils that con- 

 tain little clay and do not, therefore, run together very compactly. 

 There is, however, a large proportion of clayey soils in the Tennessee 

 and Kentucky tobacco regions in which wheat should not freeze out 

 easily. In fact, many farmers always plow their tobacco land in 

 preparing it for wheat because they believe they obtain a better 

 yield. Whether it is wise or not to plow tobacco land for wheat is a 

 question that each farmer must decide for himself. But it is certain 

 that plowing will cause the death of more than half the pupae, while 

 disking will kill very few. Upon the looser soils it would, perhaps, 

 be better to change the rotation and to sow some crop other than 

 wheat after tobacco. 



COMBATING TOBACCO HORNWORMS UPON GROWING TOBACCO. 



If tobacco is planted early the hand worming, necessary to kill all 

 worms that appear before the large emergence wave in late July 

 (Table II), can be made incidental to other processes in the growing 

 of tobacco, and will require very little additional time and labor. 

 Usually, in addition to the cultivation with farm implements, tobacco 

 will receive the following attention: Two hoeings, hilling, priming, 

 and topping, and much of the early tobacco will be suckered. During 

 these necessary operations it is very easy to discover and to kill the 

 tew tobacco worms that have appeared, but when the large wave of 

 emergence appears, hand worming will be found very costly, and in 

 some localities impossible because of the scarcity of labor. 



When tobacco worms are numerous it will require an outlay of at 

 least $8 to $10 an acre to hand-pick the worms, and frequently the 

 outlay will exceed $10 an acre. 



Use of Paris green. — After the appearance of the July and August 

 "shower of worms" an application of Paris green with a dust gun 

 (fig. 10) will be found to be the most economical means of combat. 

 In Tennessee and Kentucky Paris green is generally applied without 



