Sat 2020-01-04 
A gall wasp of species Diastrophus rubi (Hymenoptera: Cynipidae) which today (2020-01-04) emerged from the bramble gall that I collected in Thames Valley Park on 2019-08-26 (see here for a picture of the gall).
Identification based on the gall key of Redfern and Shirley, 2011.
Thu 2019-12-26 
A male Hydrellia griseola (Diptera: Ephydridae) swept from long grass. The larvae mine the leaves of various grasses and other plants (see the species' pages at UK Fly Mines and Plant Miners of Europe).
Identified using the unpublished key of Drake, 2006 (updated in 2013).
Specimen taken in Whiteknights Park, Reading, UK on 2019-12-25.
Sat 2019-08-31 
Another bivoltine species, at least in southern UK. Again based on specimens collected between 2014 and 2019, mostly in the Reading area but with a few from north Yorkshire and a few from the New Forest.
Mon 2019-08-19 More seasonal frequency plots for Muscid flies: First Eudasyphora cyanella which is commonest in spring:
And, second, the closely related Eudasyphora cyanicolor which is commonest in autumn:
These are from flies caught between 2014 and 2019 mainly on the Reading area but with with some from North Yorkshire and the New Forest.
Sat 2019-08-17 
I have written a little script to help me create plots showing the seasonal variation in the numbers of various species of fly I have collected.
Most species show a large peak in numbers in late spring or early summer with none or very few in winter. The Muscid fly Phaonia subventa is unusual in showing fewer flies in the summer than in the winter. I had noticed that it was one of the most common woodland flies in winter (I have seen them on Christmas day morning, sunning themselves on tree trunks when the temperature was below 5C) but I hadn't realised, until I saw the above plot, that they seem to almost completely disappear during the summer months. This might be a consequence of the dry summers we have had in the south of England in the past few years.
My script is still a bit primitive (it is written in Gnu Awk!) and I intend to tidy it up and extend it (and maybe rewrite it in Rust). But if you are interested you can find a copy in the Github repository where I store the catalog of my fly collection (https://github.com/tristrambrelstaff/flies). The script is mplot.awk.
