170 



THE AGRICULTURAL NEWS. 



May 29, 1909. 



INSECT NOTES. 



"Warble Flies. 



The Agricultural Superintendent at St. Lm-ia 

 recently forwarded to the Head Office insects taken 

 from the backs and flanks of the Ayrshire cows at the 

 Agricultural School at Union. In the letter forwarded 

 at the same time Mr. Moore states: ' I am of opinion 

 that they are maggots of the Warble Fly. The cows 

 arrived here from Canada last August, and the maggots 

 are maturing now. so I conclude, as they are found only 

 on the imported animals, that the eggs were in thecow.s 

 on arrival. August to September is, I think, the egg 

 season for this Hy, and April is the season for the 

 maturing of the maggots. We .ire trying to capture 

 all the maggots by squeezing them out as soon as ripe 

 enough. Each puncture is then dressed with a disin- 

 fectant to keep off the screw worm Hy.' 



^[r. Moore was correct in supposing the insects to be 

 the warble ffy, and that the cows were infected before their 

 arrival in the colony. The ox warble flies belong to two very 

 closely related species, Hijjiixh'rina hovis and Hypoiierma 

 Umntii. Both si)ecie.s are widely distributed, and as they 

 are alike in the general points of life-history, method of 

 attack, and damage done, and as similar remedies may be 

 used for their control, they can be dealt with in this paper 

 under the common term <if warble flies. 



The female warble Hies deposit their eggs on the hair of 

 the shoulders, neck, and groins of cattle. The eggs or the newly 

 hatched larvae are licked off and swallowed by the animal, 

 and from the alimentary canal the maggots make their way 

 to the subcutaneous tissue along the back. 



Several months elapse from the time when the animal 

 swallows the insect before the lattoi' arrives at its destination 

 in the back of its host. 



Here development is rapid, and after some weeks the 

 larvae make their way out through the skin of the animal, 

 and fall to the ground. The lar\ae seek a suitable place, 

 and enter the ground, where they pupate at a depth of from 

 1 to 2 inches below the surface. About a month later the 

 adult flics emerge and mate, and the females immediately set 

 about the bu.sine.ss of egg-laying. 



The usual time for the appparance of the adult warble 

 flies in America is during the sununer months, when the 

 eggs are deposited, and the young larvae are taken into the 

 mouth of the cattle not later than October. In .January 

 small .swellings begin to appear along the back, and by April 

 •or May the swellings are large, and the full grown larvae are 

 ready to leave the animals and enter the ground to pupate. 



PRKVtNTION .\NI) UKMKIUHS. 



When the warble flies are very abundant they may be 

 jjreventcd from laying eggs on the cattli>, by coating the 

 necks and backs of the animals each week during the egg- 

 laying jieriod with a repcllant mi.\ture. The following is 

 recommended : — 



Sulphur, 4 oz. 



Spirits of tar, 1 gill. 



Whale oil, 1 ijuart. 

 It is stated that the warble Hies will not Hy over water, 

 nor follow cattle into dcej) shade for the purpo.se of egg-lay- 

 ing, so that the attacks of these pests are liable to be less 

 where cattle have access to deep-shade, and ponds of water 

 in wliicli they can wade. 



When the swellings on the backs of the animals are first 

 seen, as in January, a very light rubbing with kerosene will 

 kill the grubs. This is due to the fact that the kerosene 

 enters the small holes in the skin of the cattle through which 

 the insect breathes. Later in the year, March or April, any 

 larvae which are still to be found in the back of the animals 

 should be squeezed out ami destroyed. 



Mosquitos at St. Vincent. 



]\Ir. W, N. Sands, Agricultural Superintendent of 

 St. Vincent, has sent in the accompanying notes in 

 reference to the vttrious species of mosquitos that are 

 found in the island: — 



The following mos<piitos are known to occur in 

 St. Vincent, and Dr. ('. \V. Branch. M.B.. CM., who is 

 making a .systematic study of them, has kindly supplied me 

 with their names : 



1. The common nialaiia-canying mo>(piito — Celliii, 



(Anopheles) ni-'ii/riilnifix. 



2. Wild pine juosquito, \\'iif<,iiiiiiii sp. 



•J. Vellow fever mosquito, Sft'ijiniiyid ci/njnis (fasciata). 



4. Steel-blue bush mosquito. H<iem/t</i/i/iii< sp. 



5. Kilaria mosquito. Cider fati;/anf. 



(). ('rab-hole mosquito, D'inocrrites sp. 

 A study of the habits of the two first mentioned has 

 Ijrought to light the one or two interesting points I now 

 wish to record. 



For some time past a small, and nearly l)lack mosquito 

 hail been commonly observed at the Botanic Oardens, where 

 it attacked us most persistently, and it was also seen feeding 

 on domestic animals. After searching likely places without 

 result, I e.xamined various plants which were so modified as 

 to hold water, and at last foiuid larvae in abundance in 

 water which had collected at the liases of the leaves of the 

 so-called ' Wild Pines.' 'I'hese epiphytic bronieliads occur in 

 large numbers on various trees, and l>elong to various species 

 of PIti-iiirnia, Aerhnun, and Tillmxhia. Nearly every plant 

 with water that I e.\anii)ied contained larvae — even those 

 brought down hon\ a height of ."50 to 40 feet. 



Only this one species of mosi|uito has so far been found in 

 these ' Wild Pines.' Although it is not known as a carrier of 

 disease, still it might.be, and it is obvious that to avoid 

 annoyance it is desirable to clestmy the plants in which they 

 bleed. This is now being done in Kingstown, the Botanic 

 (lardens, and other jilaces. 



The Entomologist has supplied the following note 

 for addition to th^ above : — 



in addition to the species given by Dr. Branch there 

 are .several other mosquitos listed in Theobald's ^/oii(i;/r>iji/t 

 oil. the Viiliridiu- of 'III Wmlil as occurring in St. Vincent. 

 Theobald's list is as follows : - 



.]ff'/iirhinii.'!port(>im n.-'is ( 'iilt.r fm/iti'tirtis 



Ai'iic-i jnHurhitus Delnorcritia C'lnrer 



Cf/lia nrf/i/roiarsix Ifnemoiioiiiis Cyniiens 



Cellia it/liipes Stei/oiiii/ia tasn'titu 



(Jitle.r jHilux- I'rtinotdrtii'i Loini 



From a comjiarison of these lists it will be seen that 

 there are apparently si.\ .species known in addition to the six 

 given in Dr. llranch-s list. With -so many kinds of mo.squitos 

 existing in a small i.sland it is certiiinly worth while to tiike 

 all possible precaution- against them. Only a few are known 

 to be <-arriers of disea.se, but they are all pi-etty sure to be 

 annoying, and some of them may later be jjroved to liave 

 a relation to the spread of disease not at present suspected. 



