254 



The common spinning-mite, Tefranychus telariiis, L., has only been 

 recorded from park trees, such as hme, elm, maple and bird-cherry. In 

 Sweden, no damage caused by this species has been recorded earlier 

 than in the end of August and the beginning of September ; in several 

 instances the trees, especially the limes, were entirely clothed by the 

 webs of the mites. As legards remedies, sprinkling with water in 

 greenhouses and hot-beds in many instances held the mites in check. 

 Spraying with quassia and nicotine emulsions gives good results, not 

 only against the greenhouse spinning-mite, but also against the 

 fruit-tree mite. On the other hand, lime-water as a dormant spray 

 against the latter, proved useless. 



The experiments conducted at the same time against the gooseberry 

 mite, Bryohia praetiosa, K., gave the following results. Using lime- 

 sulphur spray 1 to 5 (21° Be.) 8*5 per cent, of the mites survived ; 

 when the strength 1 to 10 was used, 8 per cent, survived. The mites 

 became pasted to the leaves and died ; the bushes were however too 

 thick, which made it difficult to wet all the leaves. In order to increase 

 the wetting power of the fluid, Vermorel and Dantony's method of 

 adding gelatine was adopted (10-15 grams to 100 litres of water), the 

 concentration being 1 to 20 of the spray, and quassia and nicotine were 

 used for comparison. The number of mites, which on the unsprayed 

 bushes was 18"6 per leaf, after the spraying diminished to 1, when lime- 

 sulphur spray was used, to 2"6 with quassia and 2'8 with nicotine, 

 the lime-sulphur spray thus proving the best. Againsb the green- 

 house mite on cucumber, a still weaker solution of lime-sulphur emulsion 

 spray was used, 1 to 40, with addition of gelatine and quassia nicotine 

 emulsion, 40 grams per litre. The result surpassed all expectations ; 

 the spray covered the leaves completely with a thin film and the 

 examination on the following day revealed the fact that all of the 

 mites were dead. An examination a fortnight later showed that 

 all the eggs were also destroyed. 



Tragardh (I.). Frukttradskvalstret {Paratetranychus jpilosus, C. & F.) 

 [The fruit-tree spinning-mite]. — Sveriges Pomologiska Forenings 

 Argskrift, Stockholm, 1915, pp. 29-31, 1 fig. 



The eggs of this species hibernate, often in great numbers, on the 

 branches especially of apple and plum trees. The eggs hatch at 

 the beginning of May and during the summer there are about 

 four generations. The occurrence of this mite is greatly influenced 

 by climatic conditions, attacks having been recorded only when 

 drought and w^arm weather prevail. The numbers of P. pilosus 

 appear to be greatest at the end of June and the beginning of July, 

 no damage having been recorded after that time. From this it 

 would appear that the factors controlling the mite after that date 

 are able to exercise an effective check. As a result of the attack, the 

 leaves turn yellow and finally drop Winter spraying with 5 per cent, 

 carbolineum is recommended, if the eggs are detected. Later, spraying 

 with quassia emulsion and gelatine is useful. 



