346 



THE AGRICCTLTURAL NEWS. 



OCTOBEE 28. 1911, 



INSECT NOTES. 



THE CONTROL OF THE ARGENTINE ANT. 



A brief account of the Argentine ant (Lidomyrmex 

 Immiliti, Mayr) was given in the Aqricultural Xeirs for April 

 18, 1908 (see Vol. VII, p. 122). 'At that time thi.s insect 

 was attracting attention in the southern part of the United 

 States, chiefly on account of its depredations on household 

 supplies, and the stock-in-trade of the grocers, bakers, 

 butchers, etc , but it was also becoming a serious agricultural 

 pest. The Argentine ant fosters and protects the cotton 

 aphis and the pink mealy bug of the sugar cane, with the 

 result that the latter insect has become a much more impor- 

 tant pest of sugar-cane than it was formerly, and it is feared 

 that the same may be true of the cotton aphis, in a few years. 

 For some three years or more, the Argentine ant has 

 been known to occur in Southern California, and in 1910 

 a bulletin on the control of this insect was published by 

 Professor C. \V. Woodworth, Entomologist of the Agricultural 

 Experiment Station^ of the University of California (Bulletin 

 207, October 1910). 



In this Bulletin, Professor Wood worth recommended the 

 use of dilute poison in a syrup of sugar, placed in receptacles 

 in such a manner that the ants could get to it, and carry it 

 in a continuous supply to their nests, when it might be fed 

 to queens and larvae. 



By this means it was found that the insects were gradu- 

 ally killed out, the small amount of arsenic not being suffi- 

 cient to poison the workers inmiediately, so that the destruc- 

 tion of the nests was retarded; but the continuous supply of 

 this substance fed to the young insects resulted in the final 

 destruction of the nest. 



In an article entitled Field Work in the Control of the 

 Argentine Ant, which appeared in the Journal of Economic 

 Entomolofjy, Vol. IV, p. 353 (August 1911), Mr. L. J. 

 Nickels, also of the E.vperiment Station of the University of 

 California, gives some interesting results as to the use of 

 the poison recommended by Professor ^\'oodworth. 



The poison bait was prepared by using 20 lb. of sugar, 

 (i to 7 lb. of water and 1 oz. of sodium arsenite. The sugar 

 and water were lieated for about three hours over a water 

 bath, and the .sodium arsenite was dissolved, separately from 

 the sugar, in a small (|uantity of hot water. The syrup and 

 poison were then thoroughly lui.ved. 



The poison bait was apjilied in the following manner. 

 Suitable receptacles were employed in the form of jam pots 

 or fruit jars with metal screw tops, entrance to which was 

 provided by means of four small holes in the metal cover. 

 A piece of sponge about half the size of the interior of the 

 jar was placed in the jar and saturated with the poison syrup. 

 The jars, thus charged, were placed in situations where 

 the ants were known to be abundant. 



The amount of poi.son syrup made from the quantities 

 of materials mentioned above, and 10 lb. of sponges, were 

 found to be sufficient for charging 300 jars. 



The first .systematic work in the extermination of these 

 ants in the trial.s under review was undertaken in a hotel, 

 which was badly infested, in the city of lierkeley, California; 

 this was considered the most difficult situation within the area 

 to be operated on. Fifty jars were distributed throughout 

 the hotel; about half of these were visited by the ants, 

 but only three were attended to by them constantly. Within 

 ten weeks from the beginning of the work, the last of the ants 

 liad disiiiipeared. This is considered rather remarkable since 

 only about {-Hi. of .syrup was actually consumed. The cost 

 of freeing this hotel of these objectionable insects was only 



825-00— a very small amount when the damage and discom- 

 fort formerly occasioned by the ants are taken into con- 

 sideration. 



Similar encouraging results were obtained m dwelling 

 houses, groceries and bakeries, and the ants were also 

 exterminated in open lots within the area covered by the 

 experiments. 



Mr. Nickels considers the facts now established, that 

 the Argentine ant can be exterminated on a given area, and 

 that it can be prevented from spreading. 



The Argentine ant has never been recorded from the 

 West Indies, and while there seems to be very little chance 

 of the introduction of this insect into these islands, it should 

 always be borne in mind that there is a possibility of the 

 occurrence of this. Merchandise of all kinds may harbour the 

 pest, but it is considered that manure and nursery stock are 

 most likely to be the means by which it is introduced into 

 new localities, while food supplies of all sorts may serve in 

 this connexion. 



The Argentine ant is an extremely serious pest, and if 

 introduced should be dealt with most rigorously. The appear- 

 ance of any ant making an unusual development in these 

 islands should be reported, in order that it may be definitely 

 ascertained whether or not the in.sect is the Argentine ant, 

 since it is most important that control measures should be 

 adopted as soon as possible after the first infestation occurs. 



MOSQUITO-DESTROYING FISH. 



In the Bulletin of Entomological Research for July last 

 (see Vol. II, Part 2), an article appears by Dr. W. B. Graham, 

 Director of the Medical Research Institute, Lagos, entitled 

 A Fish that Preys on Mos(|uito Larvae in Southern Nigeria. 



This fish is related to the Millions of Barbados and the 

 West Indies, belonging to the same family — the Cyprinodon- 

 tidae. It has been studied by Mr. G. A. Boulenger, of the 

 British Museum, who has described it as a new species under 

 the name Haplochilvi </ra//fimi. 



Dr. Graham was led to the discovery of this fish by the 

 complete absence, from a swamp, of mosquito larvae. The 

 pools of water in the swamps seemed ideal breeding places 

 for mosquitoes, but there were no larvae to be found. There 

 was no species of fish present other than the Haplochiius. 



Mosquito larvae were greedily eaten by the fish, in the 

 laboratory; but they did not seem to recognize mosquito 

 pupae as being suitable for food. 



A peculiar characteristic of these Nigerian fish is their 

 power of leaping from the water to a distance of from I to 

 2 feet. Dr. (Jraham considers that by means of this |..>wer 

 of leaping the Haplochiius is enabled to pass from one small 

 pool to another, even when the water is low and the oppor- 

 tunity for swimming from one to another does not exist. 



It is suggested that this fish should be used in pools 

 free from other kinds, and in cisterns, barrels and similar 

 situations. 



In the .same number of the Bulletin of Entomolo(iical 

 Research, there i.s a note on two species of cyprinodont fishes 

 in Uganda, with whiiOi Mr. C. C. Gowdey, Government 

 Entomologist, has conducted experiments as to their capacity 

 for mo.squito control. He finds that they devour mo.squitck 

 larvae voraciously, but he is of opinion that they will not [ilay 

 such an important part in the centrol of the insect as the 

 Millions in Barbados, since in Uganda, he states, ' there are 

 numerous swamps and rivers overgrown with papyrus and 

 reed like grasses, in which n\osquito larvae are abundant, and 

 in which these cyprinodonts are not found and will not live.' 



