Malaria mosquito survey of irrigation areas in the Murray River District / by F.H. Taylor.

  • Taylor, F. H.
Date:
1917
Catalogue details

Licence: Public Domain Mark

Credit: Malaria mosquito survey of irrigation areas in the Murray River District / by F.H. Taylor. Source: Wellcome Collection.

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    Po while on one occasion seventeen were taken; the average number of larve taken being eight to a scoop. On no occasion were less than three taken at a time. Culicine larvee were abundant, some parts of the water being black with the larve and pupe. Adult A.(Nyssorhynchus) annulipes were found here sheltering on the edges of the growing crops. Five were taken, the time being a little before noon. The small irrigating channels in this part were somewhat heavily infested with Anopheline larvee. Twelve of these channels were searched in various parts, and it was always easy to find the larve sheltering amongst the grass and reeds growing in the water. One of these channels in particular contained large numbers of Anopheline larve, six consecutive dips of the scoop, in about 100 yards of channel, capturing larve in the following numbers :— 7, 19, 11, 41, 27, and 32. Only once were less than ten larve taken at each dip of the scoop in these channels, and on one 59 were taken. This channel, which was on the edge of a standing crop, was well protected from the wind both by its banks and by the growth of herbage all over it. The nearest house was about a quarter of a mile distant. Culicine larvee were not in such numbers as the Anopheline. Here also two adult Anopheline were taken during the afternoon. Somewhat further down the road both Anopheline and Culicone larvee were found in the drains on each side of the road. The Culscone larvee were much the commoner, and were taken in numbers varying from fifteen to over 100 at each dip of the scoop. The Anopheline larvee were found in numbers varying from one to eight larve to each dip of the scoop. Similar conditions to the above prevailed in all other parts of the area examined in regard both to Anopheline and Culicine larve and the quantity of water lying about. Culicine egg rafts were also moderately common in most of the channels, drains, &c., three or four being found every foot or so wherever examined. Adult mosquitoes of the Culicine group were extremely common, rising in clouds when disturbed from their shelter amongst the reeds, grass, &c., on the sides of the channels and other collections of water. A. (Nyssorhynchus) annulipes was not so common as at Bamawm. Being a frail mosquito, easily buffeted by the wind, it is probable that the strong winds were a determining factor in the smallness of the numbers taken. The number of specimens captured on seven consecutive evenings indoors being—5, 32, 10, 14, 9, 25,and 19, total 114; average per evening 16. The number of males was 22. 58 per cent. of the females were gorged with blood. Summary. It is necessary to state that weather conditions were very adverse to the work in hand during my stay in Echuca, as heavy rain fell on several occasions and strong winds prevailed almost continuously. Under these conditions it was not surprising to find that the Anopheline adults were scarce. Culicine adults were rarely seen on the wing, but were abundant amongst the long grass and reeds. However, judging from the number of Anopheline larvee seen, it is, I think, reasonable to assume that A. (Nyssorhynchus) annulipes, Walker, is a fairly common mosquito in the Echuca North Settlement. The mosquitoes found in the district were A. (Nyssorhynchus) annulipes, Culicada sp., and Culex sp.
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