The Zika virus continues to make a nuisance of itself although we know not much more about it now than we did three months ago, or for that matter 30 years ago. The Centre for Disease Control and Prevention in Atlanta are monitoring its spread very closely, as are the World Health Organisation. Academics and researchers are working as fast as they can to create solutions for containment and eradication. I'm here to help.
While leafing through the Times from a hundred years ago today, which is infinitely more interesting and informative than is the 2016 version, I came across an article which I share with you below which suggests a certain type of dragon-fly and ducks have a positively catastrophic effect on mossies. It only leaves me to advise anyone travelling to affected tropical parts to go armed with packets of Silk Cut and bottles of Avon's Skin so Soft. If that stuff can see off those tenacious bastard midges in the Highlands it'll see off anything.
HEALTH IN THE TROPICS; NATURAL ENEMIES OF THE MOSQUITO.
The progress of tropical medicine is, like its beginning, full of interest, and its importance cannot be exaggerated, for the future of the white man in the tropics depends upon it. There are many lesser chapters in the great romance which have had too little attention bestowed upon them; one of these is the chapter in which it is told how by following nature closely it may be possible to "set a thief to catch a thief." An experiment was tried along these lines some time ago. It was observed that the little fish known as 'millions" are very destructive of the larvae of insects maturing in water. The idea was that if the fish could be got to live in pools where mosquitoes deposit their eggs a distinct reduction in mosquito-borne disease might be secured. The "millions" were brought in tanks and placed in the pools. Unhappily they seemed die off. More recently, however, these pools, supposed to have been emptied, have been found to contain the fish, and it is suggested that a few hardy specimens have managed to become acclimatised and will form the beginning of large shoals. The result of this work should prove, interesting.
In the second report on Glossina Investigations in Nyasaland, published in the Bulletin of Entomological Research, an observer relates the remarkable way in which a "dragon-fly preys upon the tsetse fly." He says, “I saw one, of these dragon-flies, which had been following and hovering round the party of six boys with me, suddenly swoop down and take a tsetse from the back of one of the boys, who was stooping at a pool to drink, its movements being extremely rapid. It settled on the grass near and commenced to devour its prey. Each dragon-fly accompanied our party for some little distance, obviously expecting to find its prey in our vicinity.’
The dragon-flies seem to take the tsetse, whether it is in a full or an empty condition. 'The writer reported on 21 cases he saw of dragon-flies taking tsetse flies. The insect is described as "indefatigable in its work." The females feed and oviposit readily in captivity, so that the question of once more "setting the thief" to work presents itself in practical form. Apparently the attacks on the tsetse are made by one special form of dragon-fly, Orthetrum crysostignia, because another form which was on one occasion observed to attack the fly behaved in so clumsy a fashion as to convince the observer that it was a novice.
An experiment described by the Colonial Journal is of interest as illustrating the same principle. Two pools of equal area were made in a stream in a mosquito region. Ducks were placed in one and fish in the other. The first pool was quickly cleared of mosquitoes; the second, in which were the fish, remained uncleared, all the mosquitoes duly became mature. Wild ducks were then introduced, and it was found that they seemed to prefer the insects to all other form of food. After two days all the larvae had been destroyed. 'These experiments," comments the Journal of Tropical Medicine and Hygiene, "confirm the observations of William Lockwood, who found that the duck was particularly adapted to devouring the larvae on the surface of water, and of the duck who found mosquitoes in the gizzard of a wild duck.'
There we go. Now if we can just redirect a few million ducks from the menu's of restaurants in Bejing to the America's, (and avoid them ending up on the menus of restaurants in Brazil), and breed bezillions of dragon-flies we will, in partnership with the Times of one hundred years ago today, have the problem boxed off.