Wed 2012-05-02 
After a few days of heavy rain, Monday was warm and sunny. The ground was still damp and there were large puddles here and there but the spring insects were out in large numbers. This is a male Leucozona lucorum (Diptera: Syrphidae) feeding on lady's smock (Cardamine pratensis).
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-04-30.
Tue 2012-05-01 
A small moth, probably Aspilapteryx tringipennella (Lepidoptera: Gracillariidae). The larvae of this moth mine the leaves of ribwort plantain (Plantago lanceolata).
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-04-29.
Mon 2012-04-30 
From two years ago: a female Volucella zonaria (Diptera: Syrphidae). A hornet-mimic.
Photo taken in the Wilderness, Whiteknights Park, Reading University grounds, Reading, UK on 2010-07-25.
Sun 2012-04-29 
A yellow soldier beetle, probably Cantharis decipiens (Coleoptera: Cantharidae). Recognizable by the pattern of black and yellow on the pronotum (the plate just behind the head).
Compare with the similar Rhagonycha lignosa. There are several keys to UK soldier beetles available out on the web: here, here and here, for example.
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-04-27.
Sat 2012-04-28 
From a walk around the lakes yesterday afternoon: my first Tachina lurida (Diptera: Tachinidae). A rather teneral female that must have just emerged from its host, the host probably being the larva of a Noctuid moth. The black lump on the fly's face seems to be the ptilinum which it inflated to break out of its pupa (which was probably itself still inside the empty shell of the host).
Tachina ursina is similar but has a whitish band near the tip of the abdomen and generally is less orange-looking (though see here).
Identification confirmed by Chris Raper here at Diptera.info.
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-04-27.
