Viktor Sten wrote: > In 1951 the entomologist N. Tinbergen showed that a wasp Philanthus > Triangulum (which digs holes in the ground for burying prey insects as food > > for its larvae) uses a mental picture of the location of the dug hole, to > find it on return with prey. If one were to search on Tinbergen on say > google.com the said picture is likely to be found. At the urging of this interesting tip, I did a search, which turned up two of the original articles by Nicolaas Tinbergen, published in German Journals. These are: Tinbergen, N. and W. Kruyt 1938. Zeitschrift f. Vergleich. Physiol. 25:292. "Uber die Orientierung des Bienenwolfes (Philanthrus triangularus Fabr.) III. Die Bevorzugung bestimmter Wegmarken. and Tinbergen, N., and W. Kruyt 1938. Biol. Zentr. 58:425. "Uber die Orientierung des Bienenwolfes (Philanthrus triangularus Fabr.) IV. Heimflug aus bekannten Gebiet. Ted Fischer Dexter, Michigan USA