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Ommatius Robber Fly with Crane Fly

Ommatius coeraebus

Family: Asilidae

Order: Diptera

 

There are 17 known species of the genus Ommatius, the plume tops, in Australia. Although a couple have some similarities, only coeraebus is recorded in south NSW.

 

Note the "beard" of setae around the face, neck and rostrum. It is believed that these setae provide some protection from damage by their prey.

 

They are active predators, mainly of flying insects, and they appear to be unselective in prey species. Their prey does include members of their own species, often with a female predating a smaller male that attempted to mate. Their long legs can be used to capture other insects in flight.

 

In this case, the prey is small Crane Fly. The prey has been pierced with the rostrum, allowing the Robber Fly to inject it with a cocktail of proteolytic enzymes and neurotoxins. The liquified contents of the fly will then be sucked up through the rostrum.

 

The cocktail of toxins include molecules that have not been found elsewhere, indicating that Asilidae toxins emerged from a unique evolutionary pathway

(Drukewitz et al, 2018).

 

The two insects have been recorded in separate iNaturalist observations:

 

inaturalist.ala.org.au/observations/263037364

 

inaturalist.ala.org.au/observations/263037071

 

I photographed the same species 20 kilometres away predating on a small Thynnid wasp:

 

www.flickr.com/photos/philipnsw/54406966134/in/dateposted/

 

 

References:

 

Drukewitz SH, Fuhrmann N, Undheim EAB, Blanke A, Giribaldi J, Mary R, Laconde G, Dutertre S, von Reumont BM. A Dipteran's Novel Sucker Punch: Evolution of Arthropod Atypical Venom with a Neurotoxic Component in Robber Flies (Asilidae, Diptera). Toxins (Basel). 2018 Jan 5;10(1):29. doi: 10.3390/toxins10010029. PMID: 29303983; PMCID: PMC5793116.

 

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Uploaded on March 22, 2025