Posted by: scrubmuncher | September 19, 2012

Mini-hawks

In one of my older posts I banged on about the hunting prowess of some of the solitary wasps and I alluded to the visual acuity of these mini-hawks.

This post concerns Ectemnius wasps in particular. These have to be right up there amongst my favourite animals. If you’ve ever observed these wasps you can’t help feeling they’re rather smart. Sharp-eyed, they watch their surroundings intently, their little heads flicking this way and that in search of mates, prey and enemies.

To give you a better idea of just how good the vision of these insects is I took the liberty of photographing their heads through a microscope. You’ll see from the photos below that their eyes are relatively enormous and are composed of hundreds of individual facets (ommatidia). There’s no question that eyes of this type are second to none when it comes to detecting movement, but they must also be able to form pretty decent images if the fussy dietary requirements of these wasps are anything to go by. Ectemnius wasps prey on flies, typically hoverflies, but also muscids, etc. which are masters of the air in their own right, so hunting them, often on the wing, requires an amazing coordination of flight and vision. The images formed in the brains of these wasps from the information streaming in through their compound eyes must be sufficiently detailed to allow them to single out their prey from inanimate objects and other similarly sized insects.

The massive compound eyes of a predatory solitary wasp (female Ectemnius cephalotes). Note the fine silvery ‘moustache’ (Ross Piper).

If you were a hoverfly you would not want one of these bearing down on you. The fixed gaze of a female Ectemnius continuus (Ross Piper).

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Responses

  1. Amazing creatures!

  2. - and photos, by the way.

    • Thanks, glad you like them.


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