41 



The Black Currant Mite. (Phytoptus ribis.) 



(PLATE VII. 1 ) 



Complaints of the prevalence of this mite in the black 

 currant plantations have come from many parts of the country 

 during the last twelve months. It has increased rapidly in the 

 past four years, having been transmitted from one place to 

 another with cuttings and young black currant bushes. In 

 some plantations this infestation has spread so fast that at least 

 50 per cent, of the buds are full of mites. A black currant 

 plantation of 20 acres in extent in Kent was visited in January 

 of this year, and it was found that almost every bud was 

 distorted from the action of the mites within it. The mites 

 were feeding upon the contents of the buds, as was seen plainly 

 when a section was placed under the lens of a microscope. The 

 effect of this will be that these buds will be abortive, or at 

 least fruitless. Stunted leaves may be put forth which will 

 in all probability fall off in the early summer, but no blossoms 

 can be formed from these infested buds. There were no eggs 

 in the infested buds that were examined in January. Examina- 

 tions iuade in the spring of last year showed that there were 

 many eggs in the infested buds, and mites in. different stages of 

 growth. Mites were also detected in the act of travelling from 

 one bud to another. At least they were upon the spaces of the 

 shoots between the buds, so that it may be inferred that they 

 were moving on in search of food. They have remarkable 

 locomotive power considering their minuteness, and get across 

 the field of the microscope so quickly that it is difficult to 

 examine them while alive. 



LIFE HISTORY. 



The Phytoptus ribis belongs to the sub-family Phytoptidre, 

 gall mites, "of the order Acarina, according to Andrew Murray's 

 classification, as given in his useful work on the Aptera written 

 in 1877. There are many species of these gall mites. One 

 attacks lime trees; another much injures the pear crop. The 

 apple, hornbeam, ye\v, alder, willow, maple, plum, birch, 

 peach, and other trees have their respective species. The vine 

 also is injured by one species, and it has been recently discovered 

 that the raspberry is attacked by one of these creatures, which 

 has been styled Phytoptus rubi. 



The Phytoptus ribis, like all the species of Phytoptidre, has 

 only four legs. These are six-jointed and furnished with 



