COTTOX OR BOLL WEEVILS 13 



It costs the planter about the same to have his fields dusted by air- 

 plane as it would for him to do the dusting himself with horse-drawn 

 machines. 



WHEN AND HOW TO USE CALCIUM ARSENATE 



There are a few simple rules that should be observed when calcium 

 arsenate dust is used against the boll weevil. They are easy to 

 remember and should be learned and carefully followed if the cotton is 

 to be saved from the weevil. 



First, get a supply of the dust and such dusting machinery as will 

 be needed. Do this long before it is time for the weevils to injure the 

 cotton. If the dust is to be put on by airplane, make arrangements 

 with one of the airplane-dusting companies in the spring before the 

 dusting is to be done. 



Next, look over the field soon after the plants have begun to put 

 on squares. After the squares have appeared in the field, examine 

 some of them every few days to see whether they have been punctured 

 by weevils (fig. 4) or have weevil grubs inside them (fig. 2). If you 

 find infested squares, examine 100 squares and count those that are 

 punctured or have grubs in them. If 10 or more of the 100 squares 

 are punctured, then it is time to begin dusting. Before beginning to 

 dust, however, examine carefully all parts of the field, at least the 4 

 corners and the middle. Sometimes only a part of the field, usually 

 the edge nearest the woods, will need to be dusted. 



You may wonder why poisoning should be delayed until so many 

 squares are infested. It is because the cotton plant has the habit of 

 putting on more squares than will ever open into blooms. A great 

 many of these squares drop off without being injured at all. So it is 

 easy to see that up to a certain point the squares which fall on account 

 of boll weevil injury are merely taking the place of the squares which 

 would fall anyway. 



Remember that dusting should be done when the air is calm 

 and the cotton plants are moist with dew. The dust sticks to the 

 plants better and less will be wasted if they are moist and no breeze 

 is blowing. It is important to dust all parts of the plants thoroughly 

 so that the weevils will get some poison wherever they feed or crawl. 

 Therefore, if hand- or power-operated machines are used, the dusting 

 will have to be done in the late afternoon, at night, or early in the 

 morning. Airplane dusting is usually done early in the morning. 



Calcium arsenate is a poison and must be handled very carefully. 

 After you use it, wash the hands well before handling food. Most 

 States now require calcium arsenate to be colored so that it will not 

 be mistaken for flour or livestock feed. 



Dust 5 to 6 pounds of the poison on each acre of cotton at a time. 

 Dust the plants again at the end of 4 or 5 days. Usually 3 or 4 dust- 

 ings will be sufficient to bring the weevil under control. If later in 

 the season the insects should get numerous enough to injure the cotton 

 bolls, dust the field once or twice more. If it rains within 24 hours 

 after dusting, redust the plants as soon as the rain stops. 



Some growers in the South Atlantic Coast States do not wait until 

 the squares are large enough to be punctured by the weevils before 

 they begin poisoning. Weevils, if present before the squares form, 

 feed on the tender leaves in the top of the plants. At this time 1 



