No abstract

Between 1925 and 1947, 9,929 samples of bees from Great Britain were examined for acarine and Nosema diseases. There was a significantly lower incidence of acarine disease in English samples than in Scottish ones, but a somewhat higher incidence of Nosema disease in England than in Scotland was not significant. A decrease in the incidence of acarine disease over the 22 years was highly significant in both England and Scotland, although the rate of decrease was not significantly different between the two countries.The average incidence of acarine disease during each month of the year was at its lowest in April, May and June, while Nosema disease reached its maximum in these three months and fell to a minimum in the autumn. Data on the seasonal incidence of Nosema disease in an apiary in Scotland between 1948 and 1953 show a similar distribution to that for Great Britain. Eesults on the incidence of both diseases throughout the year are compared with those of other authors, and possible reasons for the seasonal fluctuations are discussed.

I am indebted to the Imperial Bureau of Entomology and to Mr. F. Laing, of the British Museum, for submitting to me for classification two small lots of Thysanoptera collected by Messrs. G. Samuel and J. G. Bald, of the Waite Agricultural Research Institute, Glen Osmond, South Australia.

No abstract

The following eighteen species of Thysanoptera Terebrantia have been found on flax in the British Isles: Melanthrips fuscus (Sulzer), Aeolothrips fasciatus (L.), Anaphothrips obscurus (Müler), Aptinothrips rufus (Gmelin), Chirothrips manicatus Hal., Limothrips cerealium Hal., L. denticornis Hal., Stenothrips graminum Uzel, Taeniothrips atratus (Hal.), T. vulgatissimus (Hal.), Thrips angusticeps Uzel, T. discolor Hal., T. flavus Schrank, T. fuscipennis Hal., T. major Uzel, T. minutissimus L., T. physapus L., T. tabaci Lindeman. Each species is described briefly with notes on habits of adults and larvae, place of pupation, number of generations in the year, hibernation, time of occurrence on plants, plants and objects on which found, host plants of larvae and adults, importance to flax, record of locality and collector on flax, distribution, including altitudes, in the British Isles. More species occur in the south than in the north of Great Britain, and species common to both regions usually occur in greater numbers in the south. The insects breed on certain species of crop plants, weeds or trees of arable land. No damage of economic importance to flax by Thysanoptera has been proven in the British Isles, and the flax thrips, Thrips lini Ladureau, has not been found. Taeniothrips vulgatissimus (Hal.) may breed on flax and its adults, and those of T. atratus (Hal.) may cause superficial damage to petals of flowers. Thrips angusticeps Uzel and T. tabaci Lindeman will probably breed on flax.