Updates: Belshaw’s key

Belshaw’s 1993 key (in Handbooks for the identification of British insects: Tachinidae) is currently out of print but it is the best available for the UK tachinids. It might be possible to pick up secondhand copies if you ask around the usual book dealers or on eBay. This page contains margin notes taken from my copy and is a little out of date but you might like to note down the changes. We are currently in the process of updating the whole book for the RES and we hope that it will be published some time in 2012 or soon after.

Many modifications or notes cater for new species added to the UK list – I have noted them here but for the actual modifications see my document on the new species.

Couplet Modification
Main key #50 (b) Should read “Thorax with 3 or more katepisternal bristles” – Epicampocera, which runs through this couplet has 4 katepisternals
Main key #60 (a) Should read “arranged in an obvious, forward pointing triangle”
Main key #68 Abberant Drino lota occasionally have two small ocellar bristles so return to this couplet if you feel the specimen is neither of the choices in #69.
Main key #73 If you get to here with a specimen that has no orange on the scutellum but has crossed, up-turned apicals then you may have gone wrong at couplet #18 (hairs on facial ridge) because somePseudoperichaeta nigrolineata have bristles that only just get up half way.
Main key #74 Some Athrycia impressa have one or two hairs at the distal end of R1 but should be taken to couplet 82 (no hairs).
Main key #77 (b) [confirmatory information: V. ruralis has a stout downward curving bristle on the parafacial area and does NOT have discal bristles on T3 & T4]
Main key #85 (a) [confirmatory information: Athrycia spp. have discal bristles on T3 & T4]
Main key #95 Note a new species (Catharosia pygmaea (Fallén)) keys to this point.
Main key #117 Insert modifications for a new species, Clytiomya continua (Panzer).
Main key #144 Silly point really but if you get here with a fly that has hairy eyes and very few hairs on vein r4+5 then you went wrong at the start (hairy eyes) and you have Eriothrix prolixa!
Main key #146 The number of post-sutural dc given as a secondary feature is unreliable – Demoticus plebejus has 3 post-sutural dc
Main key #147 Watch out for a new species (Bithia demotica) here. Specimens that key to Bithia modesta should be confirmed using the Bithia key in Tschorsnig & Herting (1994).
Main key #148 Watch out for a new species (Opesia grandis) here. Specimens that key to Opesia cana should be confimed using the Opesia key in Tschorsnig & Herting (1994). Opesia cana is a spring species butOpesia grandis is found in mid-summer.
Main key #150 (a) Should read “Thorax with one pair of pre-sutural bristles” – the distinctinion between “a” and “one” is slightly ambiguous and allows for more than one pair. If you reach this point with a specimen that has more than one pair you should stop and try again – you have made a mistake earlier in the key.
Main key #154 (b) If you struggle to get a small black fly to this point you may have Paracraspedothrix montivaga (added in 2002 from specimens taken 2001). Consider:

Paracraspedothrix motivaga Phytomyptera cingulata
Mouth edge not exactly protruding but developed into a forward pointing rim – usually dark/black Mouth edge not protruding – usually grey
No apical scutellars but a long pair of sub-apicals Pair of small, diverging apical scutellars
A few fine hairs on/around node r4+5 A single large bristle on node r4+5
Bend in wing vein m usually very smooth Bend in wing vein m usually quite angular
Main key #172 Both Blepharipa schineri and Sturmia bella (Meigen) key to this point but fail both choices.
Actia key #5 (page 38) Insert modifications for a new species, Ceromya flaviseta (Villeneuve).
Athrycia key
(page 41)
Tschorsnig notes that (in addition to Belshaw’s characters) impressa has a reddish-yellow antennal segment 2 – trepida is more often black (very rarely with reddish-yellow colouration).
Ceranthia (Actia) key (page 39) Note new species (Ceranthia tristella). Check Andersen.
Entomophaga (Actia) key (page 40) Note new species here – Entomophaga sufferta. Check Andersen.
Eurithia key
(page 46)
Use genitalia figures in van Emden from couplet #9 onwards. Belshaw’s use of the presence of grey dusting is an unreliable feature. You can improve couplet #11(a) by noting that there may be grey dusting on T5 but it is always much less than on T4. Also, the number of post-sutural dc bristles is often asymetric (3 large on one side, 4 small on the other!) – check both sides.
Phasia key
(page 53)
Note new species (Phasia barbifrons (Girschner)) similar to pusilla. Check Tschorsnig & Herting.
Phryxe key
(page 54)
Note new species here – Phryxe erythrostoma (Hartig), which runs to vulgaris but differs from all other species in having claws longer than the last tarsonomere.
Also couplet 2 (a) says to look for hairs on the “underside of the subcostal vein” but figure 394 shows the position of the hairs to be along the costal vein – the correct position is the section of the costal vein between Sc and the r1. All Phryxe have small bristles along the leading edge of the costal vein but on the underside most have a clear area of vein between these and the wing surface –heraclei has some small bristlets in the area that is normally clear.
Siphona key
(page 55)
Specimens keying to S. boreata should be checked against Andersen in case they are Siphona hokkaidensis Mesnil.