The Hairy Digger Wasps of Hong Kong

Taylor, C., & C. Barthélémy. 2021. A review of the digger wasps (Insecta: Hymenoptera: Scoliidae) of Hong Kong, with description of one new species and a key to known species. European Journal of Taxonomy 786: 1–92.

On Christmas Eve, I received an e-mail from Christophe Barthélémy in Hong Kong to tell me that we'd gotten a Christmas present. Our big paper on the scoliid wasps of Hong Kong was now freely, publicly available! In this paper, we reviewed all sixteen species of Scoliidae known from the Hong Kong SAR to date, providing detailed descriptions and photographs of each. Nine of these had not previously been recorded from the region; one represented an entirely novel species. We also provided a detailed identification key and clarified some of the often convoluted taxonomy of this family.

Liacos erythrosoma, one of the larger scoliid species found in Hong Kong, copyright Jeffrey Cfy.

The Scoliidae, sometimes referred to as the hairy digger wasps or hairy flower wasps, are often large, striking wasps (the largest species found in Hong Kong get close to an inch in length) that are most often seen by observers when they visit flowers for food. They differ from other wasps in the structure of the wings which are shaped into radiating folds (often referred to as 'pseudoveins') towards the outer margins. In life, the wings have an iridescent appearance. Female scoliids are robust insects with powerful legs. This is so they can burrow into the ground in search of hosts for their larvae which develop as parasitoids on the larvae of scarabaeid beetles. Male scoliids are generally smaller and more slender than females. In some species (particularly members of the tribe Campsomerini), males can look very different from females, to the extent that it can be all but impossible to link one with the other in isolation. Males of some species can sometimes be found in large numbers as they form swarms in search of females.

Mating pair of Phalerimeris phalerata (male on top), perhaps Hong Kong's commonest scoliid species. Copyright Daphne Wong.

Christophe and I had lit upon the idea of producing a review of the family as I was attempting to identify specimens collected as part of the Hong Kong mangrove survey. Christophe already had an extensive number of scoliids as part of his own amateur collection; these formed the greater part of the material we used. One of our primary challenges was making sense of the group's taxonomy. As well as the aforementioned difficulties in matching males to females, scoliid taxonomy has its own individual tangles. The system has historically been beset with confusion, questionable decisions, and disregard for priority. Species have often been subdivided into a bewildering array of subspecies, varieties and formae, often on the basis of quite superficial differences and often with little apparent consideration as to whether they represented distinct populations (individuals of different 'subspecies' may often be found at the same location). As a result, I had to spend a lot of time digging into archaic publications to make sure they had been correctly quoted by their successors. Fortunately (as long time readers of this site will probably know), this is exactly the sort of thing that I love doing*.

*With a shout-out here to the Biodiversity Heritage Library. An absolutely brilliant resource that has just revolutionised the way we do literature research.

While I mostly took care of the taxonomy, key, and the first drafts of the descriptions, Christophe produced the photos, distribution maps, and revisions of the descriptions after I returned to Australia (including male genital dissections of all the species we had on hand). The end result is a paper I feel very proud of. Thank you to Benoit Guénard and the Entomology lab of Hong Kong University for providing access to resources, and if you have any interest in the wonderful world of Hong Kong hairy flower wasps, you can check out the final product here.