Departmental activities. 305 



Mystery Worm. — Following upon rumours of outbreaks of 

 mystery worm reaching' the Division from Southern Rhodesia, the 

 appearance of the pest in the high veld in March was anticipated. 

 A warning notice giving defensive measures was therefore issued to 

 the Press. To the close of February outbreaks in three Transvaal 

 districts have been reported. These are all in the low veld or bush- 

 veld, but later outbreaks may be expected in the high veld. The first 

 reports were received about the middle of February, and subsequently 

 reports came from Barberton, from Naboomspruit, and the valleys of 

 the Koedoes and Middle Letaba Rivers, north-east of Pietersburg. 



Cheese Mites. — The advice of the Division having been sought 

 for the prevention of damage by cheese mites in factories, especially 

 during the summer months, the following remarks, based^on American 

 records, are offered for the information of those interested. 



It is not possible to destroy mites which are actually within a 

 cheese, and there is no remedy except that of cutting out the infested 

 portion. Every cheese-room is liable to become infested, and all 

 efforts must be directed towards prevention. Nothing but the utmost 

 cleanliness and watchfulness will prevent the appearance of the mites. 

 These creatures breed all through the summer months, and in warm 

 houses they will breed in the winter. The rapidity of their multiplica- 

 tion under favouring circumstances is almost incredible. Throughout 

 the summer months they are soft-bodied and possess comparatively 

 feeble powers of locomotion. In the soft-bodied form they can endure 

 a fast of eleven weeks, and although they may not travel far at one 

 time, they may cover considerable distances in a search for food. 



The remarkable feature of their biology is the provision that a 

 number may fast for an indefinite period. Thus, when mites have 

 devoured a whole cheese and there is no more accessible food, all 

 the young ones and all the old ones die off. Those that are middle 

 aged have the power of undergoing a complete change of form, 

 acquiring a hard brown protective covering into which all the legs 

 can be withdrawn in repose. These resting forms are those that can 

 survive until food is available. They remain inert until some insect 

 or animal, such as a mouse, passes near by and then seize on to this 

 with their legs taking the chance of being transported to some new 

 supply of food. The difficulties of disinfecting are due to the extreme 

 tenacity of life of the mite in the resting stage. 



Infested rooms should be cleaned out thoroughly, fumigated with 

 sulphur, and washed with a strong soap solution. The fumigation 

 with sulphur should be at the least at the rate of two pounds to every 

 1000 cubic feet of enclosed space. 



The Vegetable Ivory Beetle (Coccotryplies dactyliperda F.). — 

 Soft-goods merchants in Durban have considerable trouble with a 

 small insect damaging the buttons (on ready-made garments) made 

 from the so-called *' vegetable ivory," which is the hard seed of a 

 palm, Hyphaena crinata. The insect is a small beetle, rather more 

 than one-sixteenth inch long. The beetles are not often seen wander- 

 ing about, and the first thing noticed usually is that the buttons are 

 attacked. Storekeepers are therefore inclined to think that the 

 buttons are infested when received. However, no trouble is experi- 

 enced with buttons in closed packages, and buttons on the clothes 

 which are most exposed are the most damaged. It is therefore 

 considered that the infestation is derived mainly from beetles on the 



