This Test Guideline is a laboratory test method, designed to assess the acute contact toxicity of pesticides and other chemicals to adult worker honeybees. Anaesthetized adult worker honeybees are exposed to five doses in a geometric series of the test substance dissolved in appropriate carrier (in total a volume of 1 ml), by direct application to the thorax (droplets). A minimum of three replicate test groups, each of ten bees, should be dosed with each test concentration. A toxic standard (usually dimethoate) should be included in the test series. The limit test corresponds to one dose level of 100 ìg active ingredient/bee. The test duration is 48h. Mortality is recorded daily during at least 48 hours and compared with control values. If the mortality rate is increasing between 24 and 48h whilst control mortality remains at an accepted level, it is appropriate to extend the duration of the test to a maximum of 96h. The results are analysed in order to calculate the LD50 at 24h and 48h and, in case the study is prolonged, at 72h and 96h.