648 



JOURNAL OF THE ROYAL HORTICULTURAL SOCTETY. 



If the water is chalky, precipitate the chalk first witli a little soda, 

 otherwise the chalky soap will obstruct the spraying machine. This 

 emulsion may be employed in a strength of one to from fifteen to twenty- 

 five of water. Petrol emulsions should not be allowed to accumulate 

 at the foot of a tree. Mixtures containing caustic soda must be care- 

 fully prepared to avoid danger to the operator. The following has been 

 found useful against red spider: — 



Eesin . . . . . . . 2,500 grammes 



Caustic soda ..... 1,250 



Fish oil ^ litre 



Water . . . . . . . 100 litres 



Put these ingredients in a pot with two litres of water; boil for 

 two hours, adding more water until the mixture becomes coffee-colour. 

 Add the rest of the water. This must be diluted for use as a spraying 

 mixture. 



An excellent insecticide may be made from one of the two follow- 

 ing formulae : — 



A. Fir-tar 1 kilo. 



Caustic soda . . . . . . 1 



B. Alkaline cresylate . . . . . 1 to 2 kilos. 

 Ordinary carb. of soda ..... 500 grammes 

 Water .100 litres 



Dissolve the carb. of soda in the water; stir in the cresylate. 

 Soft soap or, better still, fish-oil soap may be added. 

 A mixture which gave good results in a badly infested orange 

 garden in Spain was composed as follows: — 



Seal oil ...... 2,000 grammes 



Fish-oil soap . . . . . 1,000 



Caustic soda 250 ,, 



Tar oil 1,500 



Water ....... 950 litres 



Boil the other ingredients with a little of the water. When the 

 liquid is smoothly mixed, stir in the rest of the water. — M. L. H. 



Insects, Noxious, Natural Defences agrainst. By A. E. de 



Mazieres {Rev. Hort. d'Alg. p. 5; Jan. 1912; figs.) and by Dr. L. 

 Trabut {Rev. Hort. d'Alg. p. 168; June 1912; figs.).— The first of 

 these articles gives an illustrated and descriptive list of noxious insects 

 which are to be dreaded in Algeria, and of the most active enemy of 

 each among its own order. These insect allies of the horticulturist are 

 of two kinds — the predatory ones, which devour noxious insects, and 

 the parasitic ones, which are developed in the bodies of such insects 

 or of their larvae. Dr. Trabut 's article is the first of a series on some 

 imported insect pests which have multiplied alarmingly through the 

 absence of their parasites, which were left behind in their origin? 1 

 homes. The writer gives the names of these insect antidotes, and 

 describes how they may be imported and naturalized. — M. L. H. 



