Specimen Showcase | Horny Wasp

When one hears the word “#wasp”, the first image that comes to mind is one of a social yellowjacket🐝(𝘋𝘰𝘭𝘪𝘤𝘩𝘰𝘷𝘦𝘴𝘱𝘶𝘭𝘢 and 𝘝𝘦𝘴𝘱𝘶𝘭𝘢 genera) – although if you use Google, you are likely to get some pictures of bees in the mix🤷‍♂️. Wasps are, however, much more diverse, and include > 150,000 species worldwide (that’s 10 times more than all birds and mammals combined😯!), with the majority of them having a solitary lifestyle, being of significant smaller size and presenting fascinating ecology.

Hard, heavily sclerotized, narrow body shape

The genus 𝘋𝘪𝘳𝘩𝘪𝘯𝘶𝘴 (Chalcididae: Dirhininae) is one of the many genera of specialised #parasitic wasps. 𝘋𝘪𝘳𝘩𝘪𝘯𝘶𝘴 species present a worldwide distribution, although most species are encountered within tropical regions. If you have a look at the pictures here, you will note that adults have particular morphological adaptations that aid them when attempting to parasitise their host, with their #two_horned_head being the most interesting adaptions😈. Although relatively little is known about their biology, a few observations have revealed that this feature likely helps the adults to burrow into the sediment to find their hosts, where adult females will lay their eggs within their prey (#parasitism). It may also be used to escape the puparium of their hosts (the cocoon in which the larvae complete its metamorphosis into an adult) which is also aided by their hard, heavily sclerotized, narrow bodies.

Dirhinus two horned head (Note that one of the antennae is missing on the specimen)

Dirhinus close-up

Host species are primarily flies, particularly those of economic or medical interest (e.g. some of these species spreading diseases) such as in Sacrophagidae, Muscidae, Calliphoridae, some fruit fly species (Tephritidae) and butterfly parasitic (Tachinidae). One species in particular, 𝘋𝘪𝘳𝘩𝘪𝘯𝘶𝘴 𝘨𝘪𝘧𝘧𝘢𝘳𝘥𝘪𝘪, has been noted to affect #black_soldier_flies (an important agricultural pest), badly impacting soldier-fly yields, with potential implications for the industry🌾.

Another view for the dorsal horns

The species of 𝘋𝘪𝘳𝘩𝘪𝘯𝘶𝘴 and Dirhininae as a whole are not well studied in Hong Kong, with potentially some #new_species to be found💪! The species presented here may not be formally identified yet, but you can all appreciate its amazing morphology!

Text and photos by Matt Hammer