10 FARMERS BULLETIN 890. 



LEAF INJURIES AND DEFOLIATION. 



Cotton leaves are attacked by many insects, some of which are 

 usually considered of little importance, although in small areas they 

 frequently do serious injury. Dusting with arsenate of lead is 

 probably the best general remedy for cotton defoliators, such as 

 beetles, "worms," and grasshoppers. This may be done by the 

 pole-and-bag method or by the use of a dust gun with a rotary fan. 



COTTON LEAFWORM.i 



The best knoAMi defoliator of cotton is the cotton leafwonn (fig. 8), 

 sometmies called the cotton army worm. It is not present m the 

 country every year. It is a native of tropical regions, but from time 

 to time it iiies to this country and often }:)y the end of the season 

 has stripped the cotton fields of foliage. The moths are tawny, 

 with a wing expanse of slightly more than an inch. They lay 

 small green eggs singly on the leaves of cotton. The larvae are elon- 

 gate, somewhat variable in colormg, some bemg yellowish green 

 without prominent strij^es, whUe others have a black stripe dowai the 

 back with a fine central yeUow stripe. Each segment has four black 

 dots above. The larva when full grown webs one or two leaves 

 together to form a cocoon and pupates therein, lianging the pupa b}' 

 a thread to the stem. As the worms do not attack other plants and 

 do not enter the ground, cultivation and weed control are of no avail 

 against this species. When the attack is late in the season the 

 defohation is often beneficial, as it hastens the ripenmg of the fruit 

 and cuts off the food supply of the boll weevil. But often the worms 

 appear so early as to be capable of mflicting serious damage, especially 

 to late crops. In such cases it is advisable to dust with arsenate of 

 lead at the rate of about 4 pomids to the acre, more or less, dependhig 

 on the size of the cotton. It is best to apply the poison when the 

 Icfives are moist with dew and when the winds are low. The planter 

 sliould not wait until the defoliation is heavy. 



GRASSHOPPERS. 



Fre(iuently the cotton fields of Texas and sometimes of the other 

 cotton States are seriously injured by grasshoppers, among which 

 the differential grasshopper ^ (figs. 9, 10) and the Southwestern 

 lubber grasshopper^ (fig. 11) are the most injurious. 



Tliese insects lay their eggs in masses in the ground and Ihorefore 

 are subject to control by cultivation where that is possible. The 

 grasshoppers usually advance on cotton fields from near-by waste 

 places. Wliere young grasshoppers appear in great numbers they 

 may be controlled by spraying with kerosene or crude od, trapped by 

 the poisoned bait mentioned for cutworms, or crushed by drags or 



' Alabama argillacea Hubn. 2 Uelanoplus differcntialis Thos. ' Brachyslola magna Ciir. 



