Departmental Activities. 23 



CEDARA, NATAL. 



Chemical Lahoratory. — Some dip fluid from a tank in the 

 neighbourhood was analysed. This tank has not been used regularly 

 during- the past year. Although either some arsenite of soda oi fresh 

 raw dip has been added to the tank several times during this period, 

 a large proportion of the arsenic present in this tank when analysed 

 was always in the oxidized state, as shown by the following table : — 



28th October, 1919 

 1st November, ]919 

 23rd January, 1920 

 12th March ,^ 1920 



3rd June, 1920 



26th August, 1920 



8th November, 1920 ... 



The above figures prove that very often in practice a large pro- 

 portion of the arsenic in the dipping tank has become oxidized, and 

 the presence of this oxidized arsenic is not shown when testing with an 

 isometer or similar instrument. It is estimated that the oxidized 

 arsenic (in the form of arsenate of soda) has about half the killing and 

 scalding effect of unoxidized arsenic (in the foim of arsenite of soda). 

 It is therefore very important that farmers should periodically forward 

 a sample of their dip fluid to one of the laboratories of the department 

 to be analysed as a check on their own tests. 



Apiculture. — Studies of the life-history of the common bee louse 

 (Braula caeca) made during the month have cleared up some long- 

 standing errors in connection with our knowledge of this minute- 

 parasite of the bee. In the textbooks this louse is said to be nearly 

 allied to the sheep ked and to have a similar life-history. But this is 

 not so ; the eggs do not hatch inside the body of the female louse, but 

 are deposited on the brood combs where they are easily visible as 

 minute white specks. The eggs hatch out into minute maggots very 

 similar in general form to the common housefly maggot. The 

 maggots make their way into cells containing bee larvae and feed on 

 the food supplied to the bee larvae. Beyond robbing the brood of a 

 little of their food they do no harm. The Braula maggots change into 

 chrysalids inside the cells beside the bee pupae. In a few days the 

 adult bee louse leaves the chrysalis and makes "ts way on to a young 

 bee. The adult louse feeds on honey. Unless they become very 

 numerous in a hive, their presence may be disregarded. 



Keep your Jovrrwls'. The contents will be indexed every six 

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Read the Journal ! It acts as a link between you and the Depart- 

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 interests. It publishes information for the most part of an official 

 nature not otherwise readily accessible. An index will be sent you 

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 of reference. 



