A CONTRIBUTION TO OUR KNOWLEDGE OF THE 
VISUAL MEMORY OF BEES. 
By S. Graenicher. 
Various writers have undertaken an explanation of the ease 
and certainty with which bees and wasps are able to find their 
nests, even when returning from a considerable distance. Within 
the last few years a rather spirited discussion of the questions 
involved has been brought about by A. Bethe, who has maintained 
that these insects are directed to their nests by an "unknown 
power," i. e., some mysterious power unknown to us. His views 
were derived mainly from studies of the honey-bee. On the other 
side, the observations of Lubbock, Friese, von Buttel, Forel, etc., 
on bees, and of Mr. and Mrs. G. W. Peckham, Bouvier, etc., on 
wasps, have established the fact that such an insect by making a 
careful inspection of the immediate and extended neighborhood of 
the nest in all its details, and storing up the manifold visual im- 
pressions thus gathered in its memory, is enabled to find its way 
back to the nest, as also to find its way from the nest to certain 
objects of interest, flowers and other sources of food-supply, for 
example. So far as bees are concerned, the highly specialized 
among them, viz., the social bees, have been studied in this con- 
nection, in the majority of the cases the honey-bee, but occasion- 
ally also the bumble-bees. I herewith offer the results of a few 
observations relating to this subject made on a solitary bee, 
Alcidamea producta Cr., and a parasitic bee, Argyroselenis (Tri- 
epeolus) minima Rob. N 
A. Alcidamea producta Cr. _ 
The nests of this species are situated in the dry stems of 
various plants, rather frequently in those of the blackberry, and 
the bee has to excavate the pith to a depth ranging from about 
7 to 15 cm. or even more. This work of excavation requires a 
day or two, and while thus engaged the bee often interrupts its 
work, and flies around in the neighborhood, sometimes in search of 
food, but usually on a tour of inspection. On several occasions I 
have witnessed the actions of such a nest-building bee from the 
beginning on. After digging away for several minutes the bee 
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