105 



emptying'. The capacity of this shed at Tanclewanna is from 

 250 to 300 sheep, and 1,000 sheep per hour can be dipped without 

 undue haste, by four men. 



The author says that there is no reason why sheds of this kind 

 should not be built on quite a large scale, or on the other hand 

 sufficiently large to wet no more than 40 or 50 sheep at a time. 

 The cost of such a shed he puts at £10, and says that a cheap 2 in. 

 Doug-las hand-pump or no. 8 semirotary pump will give excellent 

 results. A sketch of the dip will be found in tlie February 

 number of the Queensland Agric. Jl., page 90. 



Zetek (J.). Determining the Flight of Mosquitos. — Annals Entom. 

 Soc, America, vi, no. 1, March 1913, pp. 5-21, 3 figs., 

 1 chart. 



The determination of the flight of mosquitos at Ancon, Panama 

 Canal Zone, has not only been of value from the scientific stand- 

 point, but has led to the eradication of these insects from human 

 habitations and thereby reduced the possibilities of transmission 

 of malaria, yellow fever, «S;c. 



It is essential, first of all, to have a reliable map of the region 

 selected for experimentation. It must indicate the topography, 

 roads, commercial projects and pollutions by oils or poisonous 

 refuse of streams and ponds. At the central station, and, if 

 possible, at stations where decided wind variations take place, an 

 anemometer recording* the velocity at hourly intervals and the 

 eight main directions, should be in operation. A self-recording 

 rain-gauge and porcelain cup evaporimeters should also be 

 installed. The tracing cloth should be so ruled that, in addition 

 to mosquito flight records, the quantity and duration of rainfall, 

 cloudbursts, fogs, frosts, barometric pressure and temperature 

 may be correspondingly registered. A similar tracing*, made to 

 correspond with the map, should indicate the extent of prairies, 

 forests, forest fires, drainage, marshes, the geology of the region, 

 &c. 



Of the biotic factors influencing the occurrence of mosquitos, 

 the abundance or scarcity of predaceous animals (dragon flies, 

 robber flies, ants, toads, frogs, fish, bats, &c.) should be noted, 

 and mosquito-breeding areas should be charted on small maps 

 as a result of weekly or bi-weekly surveys. Plant-associations 

 and the species of mosquitos found should also be recorded. 



For the purpose of flight-determination, larvae and pupae 

 should be collected in as large numbers as possible in a large 

 white enamelled bucket and the contents strained through a clean 

 piece of surgical gauze. This allows the debris and very young 

 larvae to escape. The gauze should then be very carefully 

 inverted over a wide-mouthed jar, so as not to injure the delicate 

 larvae, and overcrowding should be guarded against. The jars 

 are then transported to the field laboratory, and larvae and pupae 

 bred out in white enamelled or porcelain plates. Careful obser- 

 vance of the environmental requirements peculiar to each species 

 has reduced mortality among the larvae from 10 per cent, to less 

 than one per cent. Special aerating devices and breeding caches 



