Sawfly

A sawfly, probably Tenthredo maculata (Hymenoptera: Tenthredinidae).

Photos taken in Whiteknights Park, Reading, UK, on 2012-05-18.

Ladybird Beetles

A small ladybird beetle, probably a dark variant of the 10-spot ladybird, Adalia decempunctata = Adalia 10-punctata (Coleoptera: Coccinellidae).

And I think this is a light variant of the same species:

Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-05-18.

Apparently simple, but really rather deep

Computing pioneer Maurice Wilkes, in a letter to Tony Hoare from August 1981:

. . . loop invariants . . . The idea is apparently simple, but really rather deep.  Once you have grasped it fully – and I must confess that, although Floyd was very patient with me, it was some time before I did this – you will never look at the subject in the same way again.

Quoted in C. B. Jones, The Early Search for Tractable Ways of Reasoning about Programs, IEEE Annals of the History of Computing, Vol 25, No 2, pp26-49, 2003

Butterfly

A grizzled skipper butterfly, Pyrgus malvae (Lepidoptera: Hesperidae).

Photo taken in the field below Chazey Wood, near Caversham, UK, on 2012-05-13.

Ladybird Beetles

A pair of 24-spot ladybirds, Subcoccinella vigintiquatuorpunctata = Subcoccinella 24-punctata (Coleoptera: Coccinellidae).  Unlike most other ladybird beetles, which prey upon aphids, these are vegetarian.  At 3-4mm long these are distinctively smaller than the commoner Coccinella septempunctata and Harmonia axyridis (6-8mm long).

This is another one that I had seen ten minutes earlier:

Photos taken in the field below Chazey Wood, near Caversham, UK, on 2012-05-13.