72 



in them until apparently dead or for a period not exceeding one hour ; 

 in the former case the maggots were taken out of the dip and placed 

 in moist earth and left for 24 hours and the mortality tabulated. Very 

 few dips killed in less than 20 minutes and not more than 50 per cent, 

 of the maggots were killed by the various dips tried after one hour's 

 immersion. Many crawled out of the powders after 24 hours contact, 

 alive and healthy ; the addition of water in some cases caused a higher 

 mortality, in others no difference was observable. When the maggots 

 crawled out of the liquid and reached clean earth, they nearly always 

 gave rise to flies ; when they crawled out of the wool after dipping, 

 the effect was nil so far as killing the maggots was concerned. The 

 net result of the observations is to show that though dips drive out 

 the maggots, they do not help appreciably to eradicate the flies. 



Any dip must fulfil certain conditions, if it is to be of any 

 real value in deahng effectively with the fly pest, and yet not 

 have any ill effect on the wool. No dressing seems to have been 

 discovered wliich will prevent subsequent fly-blow ; the maggots 

 are driven out and the attacked part healed, but the odour seems still 

 to remain and attracts flies to the same place again. The effect on the 

 wool is often bad ; it rots and can be pulled away in lumps, in other 

 cases it mats and forms masses with soft centres which shelter maggots. 

 The effect of many dips on the animals themselves, especially if badly 

 blown and sore, is also far from good. Some dips, particularly coal tar 

 preparations and copper sulphate, mil not come out properly in the 

 scouring and their effects on the dyeing quality also require study, 

 pips are sometimes good at one time and bad at another for reasons 

 which are not very apparent. They may be connected with another 

 tfly being the cause of a second attack, the difference of climatic con- 

 ditions or lack of standardisation of the dips. The growth of the 

 wool on a merino sheep is about a quarter of an inch per month and 

 this keeps the dip further and further away from the sldn. The 

 methods of application are discussed, and of these, swabbing and 

 rubbing, if thoroughly done, seems to be the most effective. 



Hill (G. F.). Report of the Government Entomologist to the 

 Administrator of the Northern Territory of Australia for the 

 eighteen months ended 30th June 1915, pp. 43-46 of Administra- 

 tor's Keport for the year 1914-15 [sine loco], 1915. [Received 

 9th March 1916.] 



OcJilerotatus {Culicelsa) vigilax appeared in 1914 in the Botanic 

 Gardens in Darwin and adjacent mangrove swamps about 10th 

 January. Thence this mosquito spread to the town ; it increased 

 in numbers until 30th January and then gradually decreased. At the 

 end of November it was again found in the town, increasing in numbers 

 until the end of January, and then slowly disappearing. This species 

 enters houses after dusk, and remains hidden there until the foUowing 

 morning. Breeding takes place in pools of salt water in the low-lying 

 districts to the north and north-east of the town ; any reduction in 

 the numbers can therefore only be obtained by drainage of these areas. 

 Culexfatigans was less abundant than in former years. The prevalence 

 of Stegomyia fasciata in Darwin, especially during the latter part of 

 the dry season, was very marked. This species was probably 



