170 



THE AGRICULTURAL NEWS. 



May 31. 1919. 



INSECT NOTES. 



THE COTTON WORM. 



The Agricultural and Commercial Society of Nevis, at 

 a regu1.tr meeiing held in November last, passed a resolution 

 to the eflfect that the Government should request that an 

 oflicer of the Imperial Department of Agriculture be sent to 

 Nevis to investigate the life-history of the cotton worm, and 

 to advise on some more effective method of controlling this 

 pest. 



For several years the cotton worm {Alabama argi'lacea) 

 has appeared regularly in the cotton-growing islands, the 

 severity of the attack varying from season to season, and in 

 each season varying somewhat from island to island. St. 

 Vincent is the only one of the islands in which cotton is 

 grown on a large scale where the cotton worm has very 

 rarely occurred in sufficient numbers to do damage to the 

 crop, or to require applications of poison for its control. 

 Although the insect is present in the cotton fields of the 

 island, it is usually held in check to such an extent by the 

 'Jack Spaniard' {PuUfles annii,!a^is)t)i'iX it does not often 

 increase in number.* sufficiently to be a pest. 



The attacks of the cotton worm in Nevis during the 

 cotton-growiDg season of 1918 were severe, and much 

 damage is said to have been dene to the crop. The Euto- 

 mologitt on the stafTof the Imperial Dep? nraent of Agriculture 

 visited Nevis in JIarcb, and attended a meeting of the 

 Agricultural and Commercial Society. During the discussion 

 which fol'o.Yed a short address on cotton pests and the cotton 

 industry in general, it was stated by a member of the society 

 that the resolution passed at the November meeiing arose 

 from a desire to obtain information which might help cotton 

 growers to take steps to deal with the cotton worm in some 

 such manner as that proposed to be adopted in 

 the iblancl against the cotton stainer and the leaf- 

 LiiSio. ji'l'", !-y means of a campaign during the close 

 ssitaon, thus preventing, as far as possible, the carryii.<» 

 ovrr of the in.^ect from one cotton season to the next, 

 reducing the early attacks, and retarding the increase of the 

 pest. It was thu.s shown that an impression existed that the 

 cotton worm i.s carried over from season to season like the 

 cotton stainer, and that some line of action might be adopted 

 for dealing with the pest in its ofT season. 



The explanation that the cotton worm is not known to 

 carry over from one season to another in these island."!, and 

 that invasions from sources outside these islands are believed 

 to account for each season's infestation satisfied the cotton 

 growers on this point. It was then decided that 

 every effort should be made to induce all interested to 

 provide that a sufficient .supply of insecticides should be on 

 hand at the beginning of the cotton-growing season, and that 

 some means should be devised to compel the api'lication of 

 those methods of control which have been found effective in 

 Ihe West Indies. 



The new invasions by the cotton worm year after year 

 18 a matter of importance and interest. In former numbers 

 of the Agricultural Mtws (Vol. X, p. 378, and Vol. XI, 

 p.266) this subject was discussed. The remarkably severe 

 attack of the cotton worm in the cotton belt of the United 

 Slates in 1911 stimulated a considerable interest in tliis 

 insect and its habitfi. Dr. W. D. Hunter, of the United 

 States Bureau of Entomology, read a paper on the subject 

 at the meeting of the American A.saociation of Economic 

 Entomologists, held at Washington, D.C., on December 27-'J9, 

 1911 (\iAe •fouinalol Ecmomic Entomolnyy, Vol. V, p. 121). 



In this paper, Dr. Hunter stitel that afier nearly a 

 quarter of a century, during which the cotton worm had 

 attracted practically no attention, it suddenly appeared 

 in extreme abundance. This attack was ni>t foreseen in 

 any way, and the entomologists were as much surprised as 

 the cotton growers. 



The earliest seasonal record of its appearance in that year 

 came from points in Texas and Mexico near the border, 

 and not far from the coast. As early as May 20,j 

 defoliation had commenced at Brownsville, ind by June 10 

 it was complete in the majority of the fields in that 

 vicinity. In the East the first seasonal record came from 

 South Carolina, where the insect was discovered early 

 in July, but at that time it was very scarce, and it 

 was not seen in large numbers until September. About 

 this time (September 20 to October 1) enormous flights 

 of the insect took place, and the moths of the cotton worm 

 were recorded in large numbers in many localities in the 

 United States. 



In Washington, DC., large swarms of these moths 

 appeared on September 19, and at about the same time they 

 were observed in Clarkesville, Tennessee, and Dallas, Texas. 

 From September 20 until early in O^jtober they were being 

 reported in Pennsylvania, and on September 28 they 

 were found in Massachusetts. 



The following is quo ed from Dr. Hunter's paper : — 

 'Our conclusion regarditig the rr, i-in of the outbreak of 

 1911 is that it started from two infest itions. One, 

 apparently unimportant, in the eastern pirt of the 

 cotton belt, and the other, of much greater importance, 

 which began in Norihern Mexico. The filling in of 

 the intermediate territory in the .Mississippi Valley, however, 

 can har.lly be explained satisfactoril3' on iLc assumption that 

 these two invasions increased and eventually oilesced. In 

 fact the general heavy iofestatiin which became noticeable 

 throughout the South early in September ciu only be ex- 

 plained on the a'-sumption that an invasion of m)lhs from 

 across the Gulf of Mexico took place shortly before that 

 time.' 



In the discussion which followed the reaJins; of the 

 paper, the statement was made that the cotton moths never 

 hibernate in the Uni ed States, ami never fedupmuny 

 01 her food-plant than cotton. Refertnce was made to the 

 coufiicling views held in earlier yeirs ,'is to whether the 

 cotton moth hibernated in the United St^ic. At that 

 time only one entomologist of rep'ito in the United 

 States, Prof. A. 11. Grote, maintained that this did not 

 hapi'en, and it was held that all the observations made and 

 inloriuauon collected in more recent years confirmed his 

 opinion in thematter. Mr. E. A. Schwartz, of the Uniied States 

 Bureau of Entomo'ogy.who took part in thediscussion, referred 

 to -a mission on which he went in the wi.iter of 1679-80 

 for the purpose of collecting citton moihs or the r pupae He 

 travelled throughout the cotton belt, and went to the. Bahama 

 Islands, but was not able to find any trace' of the c it'on moth 

 hibernating. He stated that Piofcs.soi Grott's opii.ion was 

 now generally accepted, that the cotton mih does not 

 hibernate in the United Slates, and that invasions of this 

 insect came from some part of tropical .Anurini, probably 

 from Ikazil. In later years Mr. Scliwartz visited Cuba, 

 Guatemala, Mexico, and Panama, and his ob-ervations in 

 these localities with regard to the hibernating of the cotton 

 moth served to confirm his earlier opinion. 



From what has been stated above it will be seen that 

 the cotton moth invades the cotton-growing section of the 

 United States at different times Ihruugho t the season, but 

 in many years these invasions are not suffi ;ienlly strong to 

 cause extensive epidemics. In 1911 the cise was different 



