303 



Porter (C. E.). Dos c6ccidos nuevos para Chile. [Two Coccids new 

 to Chile.] — Bol. Museo Nacional, Santiago {Chile), v (1913), April 

 1914, pp. 363-364. [Received 14th December 1914.] 



The discovery in Chile of Asterolecaniinn variolosum, Ratz., new to 

 South America, and Dinaspis sp. are recorded. The latter was found 

 on Maytenus boaria, Mol., and is new to science 



Taylor (Miss A. M.). Eriophyes ribis (Nal.) on Ribes nigrum. — Jl. 

 Aqric. Science, Cambridge, vi, no. 2, May 1914, pp. 121-128. 

 [Reprint received 13th May 1915.] 



This paper deals with the mode of migration of Eriophyes ribis, Nal. 

 (the black currant mite), and also with its mode of existence from 

 the time when migration to other plants becomes necessary in March, 

 owing to the death of the buds on which the mites have lived for the 

 preceding nine months, to the time when they are fomid in the new 

 buds in May. In March, April and May, the mites emerge from between 

 the leaves of the deformed bud and distribute themselves over its 

 outer surface. If the temperature is low, they return to the interior 

 of the bud. Under favourable weather conditions the mites become 

 extremely active, leaving the buds and making their way down the 

 stem, but by far the greatest number crawl actively about the bud, 

 suddenly standing erect from time to time. On a calm day they may be 

 seen in this position for several minutes, apparently waiting for the 

 wind to carry them away, for distribution is effected mainly by the 

 agency of the wind. There are three other methods by which the 

 mites are distributed at this period : (1) By clinging to passing insects, 

 such as bees, thrips, etc., and being carried by them to surrounding 

 trees ; (2) by being carried up with the developing shoot, in the event 

 of the " big bud " surviving the attack, or, in the case of the bud being 

 killed, by crawhng to surrounding shoots ; (3) by springing from the 

 big bud to other parts of the tree. The two last-named methods would 

 ensure re-infestation of the attacked tree. The day temperature during 

 the migratory period varies roughly between 50° and 100° F. At 50° F. 

 few mites emerge, but when the thermometer rises above 80° the mites 

 become extremely active and the erect position is generally adopted. 

 Each bud may set free about 1,000 mites an hour under favourable 

 conditions, so that one bush may be a source of infestation to all 

 neighbouring orchards. In a cold late spring, a late exodus of the 

 mites will take place. The condition of the bud is a third factor, for 

 some buds, and the mites within them, die before conditions are 

 suitable for migration, and others, although green and succulent, 

 remain so tightly closed that the mites within are imprisoned. It would 

 appear from an experiment that no migration took place from buds 

 which were dry ; those which were nearly dry and those which were 

 closed gave approximately the same number of emerging mites, while 

 from the green expanding buds and those which were becoming dry, 

 the most active migration occurred. Mites of the genus Phyllocoptes, 

 but not Eriophyes ribis, were found under the loose bark that is shed 

 annually by the black currant. The surface of the earth round the 

 trees was examined, and although a few mites were found their numbers 

 were so small that this did riot appear to be their natural habitat. With 



