90 



THE AGraCULTURAL NEWS. 



Maecd 22. 1919. 



INSECT NOTES. 



SOME INSECT PESTS OF TROPICAL 



CROPS 



The following notes from the report of the Entomolo- 

 gist of the Uniud States Department of Agriculture, 

 for the year ended June 30, 1918, dealing with insect 

 pests affecting tropical crops, are of interest and value: — 



COTTON BOLL WEEVa KILLED BY POISON- 



One of the most striking achievementa of the Bureau 

 culminated during the year in the announcement of the value 

 of powdered lead arsenate or calcium arsenate against the 

 cotton boll weevil. After years of experimentation the 

 Bureau is now able to announce that the weevil can be killed 

 during the summer months by dusting the cotton with cither 

 of these poisons at the rate of 5B). per acre, with three to five 

 applications at weekly intervals The poisoning, to be most 

 effective, shonid be done between 4 p.m. and 9 a.m., and the 

 powder should be applied by means of a rotary dust gun 

 or by power machinery. A special power machine has been 

 developed which will cover nearly 200 acres per day. The 

 cost of treatment is about ^^1 00 per acre for application. 

 Distinct gains in yield of from 250 to 1,000 lb. of seed-cotton 

 have been obtained. It is hoped that the application of this 

 discovery will jireatly increase the yield per acre of cotton, 

 one of the most important crops of the nation. 



It may be mentioned that the cotton boll weevil 

 {A-nHiovomuB gravdis), one of the worst cotton pests 

 in the world, and which is responsible for an immense 

 amount of damage to the cotton crop of the South- 

 eastern States, has fortunately been kept out of the 

 West Indies tip to the present. It is important that 

 the United States Department of Agriculture have 

 been able to put forward a method of control. The 

 success of the method referred to above soems to be 

 dne to the thirsty habits of the insect, which sucks 

 np the dew from the surface of the plants, and thus, 

 when the plants have been dusted with the poison 

 mentioned above, the weevils imbibe their death potion^ 



SWKET POTATO WEEVIL EUADICATION. 



Following an urgent request, an emergency fund of 

 $30,000 was made available about .March 1, for an investiga- 

 tion of the sweet po'ato weevil in the States of Florida, 

 Georgia, Alabama, Mississippi, Louisiana, and Texas, which 

 might lead to its eradication and control. This has made 

 possible a preliminary farm to farm survey of all outlying 

 infested territory, definitely establishing the boundaries of 

 infestation. A series of large-scale experiments in control 

 have been undertaken at field stations in Texas, Miesissippi, 

 and Florida, and demonstration eradication prtjects have 

 been initiated in portions of I'"lorida, Georfiia, Mississippi, 

 and Alabama, the cloEe survey accomplished having est&b- 

 ished the feasibility of operations for ihjvt purpose. 



A.n educational campaign by inspectors has already been 

 productive of much benefit, and has reduced materially the 

 number of infested farms in Georgia, Alabama, and 

 Mississippi; indeed it seems probable that the completion of 

 another season's work may find the Bweet potato crop of the 

 lea.st infested of these States nearly weevil free. 



Experiments with heat curing of sweet potatoes have 

 .shown the possibility of securing a mortality of 95 per cent 

 of weevils in storage houses by carrying the tubers at a 

 temperature of 115° F., for eight days. In badly infested 

 districts in Texa?, where weevil injury is frequently 50 per 

 cent.., loss* s have been reduced to less than 10 per cent, by the 

 timely application of arsenical sprays. 



Life-history and investigations have brought forward many 

 interesting facts regarding this weevil which can be applied 

 in the coming season to g;tcellent advantage. Good progress 

 has been made in a survey of the wild food-plants of the 

 pest. On the whole, the beginning of the fiscal year 1919 

 finds the Bureau well equipped to conduct a most effective 

 campaign against this pest during the coming season. 



INVESTIGATIONS OF INSECTS AFFECTING CITROS KRUIM 

 IN CALirORNIA. 



Work in control of the two important mealy-bug enemies 

 of citrus trees has been continued during the year and has 

 resulted in notable success. The means now recommended 

 by the Department are being generally recognized as practi- 

 cable and efficient methods of handling infested orchards. 

 This is particularly] true in reference to the .so-called citrophilos 

 mealy-bug. The study of this insect was begun during the 

 year in response to a petition from citrus associations and 

 fruit exchanges in western San Bernardino County, where 

 considerable alarm had been aroused by the rapid spread and 

 great damage done by this scale insect. The citrophilua 

 mealy-bug is a comparatively new pesl, which started with an 

 invasion of a few trees in 1915, but now covers an area of 

 about 1,000 acres. A 20-acre demonstration plot has been 

 freed from this mealy-bug by the combined procedure of 

 control of the Argentine ant, spraying the trunks of the trees, 

 and utilization of predatory natural enemies. 



The important relationship of the .\rgentine ant to infes- 

 tation by mealy-bugs in southern California has necessitated 

 as a first step the control of this ant. This is accomplished 

 by the use of poisoned ant syrup. This method of control 

 has already been eitended on tipwards of 200 acres in this 

 district, and a great expansion of this work is now in progress. 



CONTROL OF THE FLUTED SCALE IN NEW ORLEANS. 



This project was completed during the year and was dis- 

 continued on June 30. It was an enterprise conducted by the 

 city of New Orleans, the State of Louisiana, and this 

 Department in oo-operation. The control of the fluted scale 

 has been accomplished in New Orleans and ueighbourine 

 places by the propagation and liberation of thousands of the 

 natural enemy of this scale insect, the Australian lady-bird 

 Novius cardinalis. Over .'500 colonies of these lady-birds were 

 liberated over an area of 40 square miles. The distribution of 

 this beneficial lady-bird has been extended to the known out- 

 lying infestations of the fluted-scale in Jjonisiana, Mississippi 

 and Texiis. In connexion with this work, some very interesting 

 studies have been made of the fluted .^calc, its lady-bird enemy 

 and particularly the symbiotic relatiou.~hip between the fluted 

 sca'e and theJArgentine aut. The results of this work demon- 

 strated that this ant, by protecting the fluted scale from its 

 natural enemies, increased the Multiplication and destructive- 



