50 Years Ago

The mandibular gland secretion of the worker honeybee Apis mellifera L., contains 10-hydroxy-Δ2-decenoic acid and ... 2-heptanone ... I have shown that 10-hydroxydecenoic acid does not repel foraging honeybees but that 2-heptanone does ... Foragers were strongly repelled by the odours of crushed heads and crushed mandibular glands, which contain both 2-heptanone ... and 10-hydroxydecenoic acid, but were unaffected by crushed thoraces. The odour of 10-hydroxydecenoic acid neither attracted nor repelled foragers, but 150 μg of 2-heptanone repelled them as strongly as either the crushed heads or the crushed mandibular glands of ten foragers. The ability of the mandibular gland secretion of a forager to repel other foragers probably depends largely, or entirely, on its content of 2-heptanone. It is unlikely that this pheromone is used by foragers to warn others away from an exhausted food source but if, as has been reported, it plays a part in colony defence, perhaps it is released by guard bees to deter potential robbers from the honey stores.

From Nature 29 October 1966

100 Years Ago

On October 20 .... large fireballs were observed. The first was seen by Mr J. E. Clark, of Purley, Surrey, and it was estimated as twice as bright as Venus ... The second was seen by Mrs. Fiammetta Wilson at Totteridge, Herts, and by Mr. Denning at Bristol. It appeared as a ball of fire streaming slowly along in a level course about 8° above the northern horizon. This fireball was at a great distance from the observers, and probably over the southern region of Scotland. It probably emanated ... from a radiant near Zeta Herculis low in the N.W. sky.

From Nature 26 October 1916 Footnote 1