Extraordinary Garden Flies

Physiphora is a small metallic fly with very impressive eyes. The larvae develop in decaying plant material. This is followed by Urophora which produces Thistle Galls, Volucella zonaria a type of Hornet Hoverfly, two Tachnid fly species etc etc.

Insect Eyes from Paxton Pits

Among the 70 or so different species that I photographed yesterday during one of our Wildlife Survey  mornings, I found this set of amazing eyes to share (Red-eyed Damselfly, Common Blue Damselfly, Snail-killing fly, Kite-tailed Robberfly, Median Wasp (at nest), Eristalis pertinax, Roesel's Bush Cricket, Speckled Bush Cricket, Cicadella viridis, and Common Darter female)

Lapwing Monocular Vision

I took a trip to Fen Drayton pits yesterday to see what was about - not much! I did spend a bit of time photographing a pair of Lapwings and got intrigued by the placement of the eyes - they can obviously see directly behind as well as in front. I then wondered what the world looks like to them and looked up on the web.

 Certain birds including snipe and some other waders have 360 degree horizontal vision and 180 degree verticelly so can detect a potential danger immediately. Their vision is monocular and so they have a harder time judging distances. Birds like raptors have their eyes placed far to the front giving them binocular vision as ours. These birds may have a 180 degree field of overall vision with much of that binocular. They have much sharper vision to the front than their monocular cousins.

The structure of a bird's eye is similar to humans but most birds' eyes are flatter than human eyes. This flatness allows birds to have a larger area in focus at one time while we focus one smaller area at a time. Cones allow the brain to perceive colours. A human may have 10,000 cones per square millimeter while some birds may have up to 120,000 per square millimeter! Birds who forage and feed in the daylight see colours very clearly from far off. In particular, they can distinguish greenish colours much better than we can. In addition, most birds have a UV sensivity with a maximum around 370 nm. This ability allows them for example a better detection of fruits or rodents (scent marks) and a better differentiation of plumage patterns.