British Insects: the Species of Odonata


L. Watson and M. J. Dallwitz


This package is generated from a DELTA database (Dallwitz 1980; Dallwitz, Paine, and Zurcher 1993). At its present stage of development, it represents a first draft attempt at an automated, interactive version of the excellent treatments by Lucas (1900) and Hammond and Gardner (in Hammond and Gardner 1977, revised by R. Merritt in 1982). Curtis’s British Entomology includes only two folios on Odonata, and it is illustrated mainly by scans of Lucas’s excellent lithographs and text figures, supplemented from Shaw and Nodder’s Naturalist’s Miscellany (1789–1813) and with a few original photos by Giles Watson.

The basic taxonomy (i.e., the descriptive characters employed, and the classification into genera and higher groupings) and the list of species of British Odonata have changed little over the past hundred years. Even the nomenclature has remained rather stable by contrast with many groups. Lucas provided first rate, detailed descriptions as well as good illustrations, while Hammond and Gardner’s beautifully illustrated and inexpensive book is outstanding in presenting taxonomy properly to amateurs with a genuine interest in natural history. The main advantage of this Intkey package over the latter publication resides in the obvious superiority (rather well exemplified in a data set such as this one) of interactive identification over printed keys. Thus, it should be unnecessary to negotiate the taxonomic hierarchy (i.e., sub-order to family to genus to species) in the time-honoured fashion, involving mandatory use of abstruse characters, in order to arrive at identifications. In the present case, for example, it is unnecessarily arduous and accident prone to commence with obscure details of wing venation, when estimating the approximate length or wingspan of an insect will reduce the list of possibilities enormously. Furthermore, in a properly designed interactive key, the errors that inevitably occur occasionally during identificatory processes are less likely to be fatal or even particularly inconvenient. A conventional key, generated from the same data, is provided here to facilitate comparison.

The encoded descriptive data on nymphs are very incomplete, being obtained mainly from printed keys; but if the main source (i.e., the Gardner key) works in practice, the present package should offer reasonable prospects for identifying them at least to generic level.

All the compilations in our ‘British Insects’ series, including this one, are readily accessible for extending, improving and making corrections. Organization under the Delta system ensures ready access for corrections and improvements. Informed criticism and constructive input are of course welcome, and will be appropriately acknowledged. Alternatively, complete Delta data sets can be donated if required for teaching purposes, or to any professional or amateur entomologist or organization interested in developing them further.

Much information on British dragonflies, with numerous excellent photographs, is available at the Web site of the British Dragonfly Society, at