378 



THE AGRICULTURAL NEWS. 



NOVBMBEE 25, 1911. 



^ /2 







INSECT NOTES. 



NOTES ON THE COTTON WORM. 



A letter received recently at the Office of the Imperial 

 Department of Agriculture, from Mr. W. D. Hunter who is 

 in charge of the southern field crop insect investigations of 

 the Bureau of Entomology of the United States Department 

 of Agriculture, states that a most extraordinary outbreak of 

 the cotton worm {Alahavia anjillacea) has been experienced 

 in the United States during the col ton-growing season just 

 past, the cotton fields from Texas to the Atlantic having 

 been completely defoliated. 



Mr. Hunter is endeavouring to ascertain the sources from 

 which the enormous numbers of these moths have come. He 

 believes that in one case they migrated into the United States 

 along the Mexican coast, and he raises the question as to 

 whether another migration may not have taken place from the 

 West Indies. 



It does not seem likely that the West Indies could have 

 furnished any large number of cotton moths during the past 

 two or three seasons, as this insect has not been very abun- 

 dant, in the Lesser Antilles at least. 



The cotton worm is known to have migrated over long 

 distances in past years, and freshly emerged moths have been 

 taken, very much to the north of the districts in which cotton 

 is grown. Up to the present time, howerer, no other food 

 plant for this insect is known, and it appears that these moths 

 must have grown to maturity within the cotton belt, and then 

 have migrated; but the perfect condition of many of the moths 

 has often led to the question as to whether these insects 

 jxissess some food plant growing further north than cotton 

 is known to grow. 



In this conne.\ion, a note by Dr. H. T. Fernald of the 

 Massachussetts Agricultural College, which appeared in 

 i^cience for October 13 may be of intere.st. Dr. I''ernald states 

 that, during the last week in September, a number of moths of 

 the cotton worm were captured at Amherst, Massachussetts. 

 The moths were very fresh and perfect, and occurred in greater 

 numbers than has before been recorded for thi.s locality. In 

 the Entoniolofjkal News for November 1911, Dr. Henry 

 Skinner contributes a note on the abundance of the cotton 

 moth in Philadelphia from September 23 to 26. 'They 

 swarmed in some parts of the city and hundreds were resting 

 head-down on the electric light [wles and on plate glass 

 windows of stores. There were many thousands of them 

 and nearly all that I saw were in perfect condition as though 

 just from the chrysalis. These moths are known to migrate 

 in numbers but it is quite strange if the great numbers seen 

 here came from the cotton districts of the South. The moths 

 in some places appeared to create considerable alarm, people 

 thinking they would cause damage to plant life here.' 



The fact that the abundance of the cotton worm has 

 been observed in these northern latitudes, at the end of the 

 season in which this insect has been so destructive in the 

 South, might indicate that it occurs there as the result of 

 migration directly from the cotton fields. On the other 

 liand, the fact that the moths were remarkable for their 

 perfection and freshness again raifes the question as to 

 whether the cotton worm has another food plant than cotton. 



The answer to this question would be of considerable interest 

 to West Indian planters for, although uncultivated or wild 

 cotton furnishes food for the cotton worm and thus helps it to 

 survive periods when no cultivated cotton is being grown, 

 it is obvious that additional food plants would be of value to 

 the cotton worm during this unfavourable period. 



SOME USEFUL INSECTICIDES. 



For several years past, the United States Department of 

 Agriculture has been conducting investigations in the control 

 of the California peach borer (Sanninoidea opatexcens), and in 

 the process of these investigations has demonstrated the use- 

 fulness of certain washes for the protection of pnuch trees. 



The borer mentioned is one of the Lepidoptera, the 

 adult being a beautiful moth and the larva or borer a cater- 

 pillar. The effect upon the peach tree however is much the 

 same as that of the cacao beetle on cacao trees, and of the 

 lime tree bark borer on lime and other citrus trees. The 

 methods of control found to be useful in California may also 

 be of value in the West Indies. 



The peach borer is controlled by the practice of digging 

 out the larvae, and the use of a wash on the trunks of the 

 trees to repel the egg-laying adult and prevent its gaining 

 an entrance. In the case of the West Indian borers there 

 are no such definite seasons for the different stages of insect 

 development as obtain farther north, and consequently a con- 

 stant look-out would have to be kept for the emergence of the 

 adult or for the appearance of infested areas on the trunks 

 of the trees. It is the general practice in cacao and lime 

 plantations to dig out borers, and after clearing away the 

 dead bark to treat the expo.sed surface with a preservative 

 such as coal tar or resin oil. 



The protective wash which has been found most useful 

 in dealing with the California peach borer is the one 

 described under the heading Formula No. I. This is a mix- 

 ture of lime and crude oil prepared as follows : — 



Formula No. I. The lime crude oil mixture. Place, 

 about 50 lb. of rock lime in a barrel and slake v.-ith 10 to 15 

 gallons of warm water; while the lime is boiling, slowly pour 

 in G or 8 gallons of heavy crude oil, and stir thoroughly. 

 Add enough water to make the whole a heavy paste. The 

 wash should be applied immediately with a heavy Inush. 



This has been found effective and is not injurious. It 

 prevents the egg-laying females from gaining access to the 

 bark of the tree and it does not seem to injure the plants. 

 Mixtures made according to Formula No. 2 and Formula 

 No. 3 have also been used, and as the)" may be applir ible in 

 certain cases in the West Indies, the directions for making are 

 given herewith. 



Formula No. 2. The limesulphur-salt mixture. Place 

 about 25 lb. of rock lime in a barrel and slake with warm 

 water. Add 2 quarts of sulphur and 2 or 3 handfuls of salt 

 while the lime is still boiling This wash is heavy, and is 

 applied with a brush. 



Formula No. 3. Lime, coal tar, and whale-oil soap. 

 Unslaked lime 50 lb., coal tar lA gallons, whale-oil soap 12 ft. 

 Slake the lime in w»rm water, and add the tar while the mix- 

 ture is boiling; dissolve the soap separately in hot water, and 

 add this to the lime solution. Add enough water to make 

 a heavy paste. 



These notes on the California peach borer, and the direc- 

 tions for making the washes according to Formulas Nos. 1, 

 2 and 3, are taken from Bulletin 97, Part IV, of the Bureau 

 of ICntomology of the United States Department of Agricul- 

 ture, entitled the California Peach B -rer, by Dudley Moulton, 



