Natural History Photographs

The superfamily Apoidea is recognized as a natural group - that is, a group sharing a common ancestor - on the basis of some structural features of the thorax. (Regrettably, I cannot show these yet from my own photographs.) Traditionally, the Apoidea comprised of two groups, the bees - family Apidae -, and the digger wasps - the Sphecidae. However, nowadays most authors think that the Sphecidae thusly conceived, the Sphecidae sensu lato, are not a natural group, because this group excludes the Bees, with which they share a common ancestor.

The cladogram below shows a recent interpretation of the relationships between digger wasps and bees (based on Evans & O'Neill 2007). In such a cladogram, the only natural groups are those that include all descendants derived from some putative common ancestor. Any branching point in a cladogram represents an ancestor; all branches that derive from it are its descendants. Groups that do not contain all descendants of an ancestor are nowadays no longer taxiconomically valid. For this reason, the group of Spheciae plus Crabronidae is no longer accepted as a valid taxon, and I better not refer to this grouping as the Sphecidae sensu lato. In line with current phylogenetic insights I seperate the digger wasps into the Sphecidae (sensu stricto) and the Crabronida. The bees are just referred to as the Apidae.

All bees share a common ancestor, and all descendants of that ancestor are in the group of the bees. This means that the bess form a natural group, but it does not clarify which rank this group gets. Since the diversity within bees is about similar to that found in other wasp families, it is defensible to give the bees the rank of a family (Gauld and Bolton 1988).

Bees share many characters that place them apart from the Digger wasps. Most chracteristically, as larva they feed on pollen, nectar and floral oil. This is the functionally most relevant feature of all bees. But there are also a number of clear morphological features specific to the bees. For instance, bees have (at least some) plumose hairs. Another important feature is that on the hind leg, the first part of the tarsus is much broader than the second to fifth part.

The Apoidea as a whole comprises some 30,000 species, with bees being in the majority with an estimated 20,000 species. Within the Sphecidae, Crabronidae and Apidae there is great variation in life history, nesting habits and behaviour.

My aim in these pages is to show some of the rich variety found in the digger wasps and bees - variety in appearence as well as in life history and behaviour.