BR. J. ENT. NAT. HIST., 6: 1993 



Geomyza majuscula (Loew, 1864). This species looks like a large tripunciaia and 

 for the small sample of majuscula that were measured, its wing and body dimensions 

 fall just beyond the range of values for tripunciaia. Apart from its larger si/e, 

 majuscula may be tentatively separated from tripunciaia in the field by the absence 

 of the basal wing spot which is usually very distinct in live tripunciaia. The thorax 

 is usually orange. Geomyza breviforceps Hackman appears to be identical to majuscula 

 and is most probably a junior synonym, as Hackman (1958) himself suggested. 



Geomyza majuscula has been recorded from Hampshire (Chandler, 1991), Suffolk, 

 Norfolk, Cambridgeshire, Dyfed, Cumbria and the Highlands. Most of the localities 

 are rich fens or pond or river margins (one with Carex, another with Phalans 

 arundinacea L.). Capture dates range from March to October. It is classified as 

 nationally scarce (Falk, 1991). 



Geomyza subnigra Drake 1992. This is a moderately uncommon species in Britain 

 and has been confused with the scarcer breviseta although some records of breviseta 

 may genuinely refer to this species. It runs to either breviseta or hendeli in the keys 

 of Collin and Czerny, depending on how well differentiated the longest subvibrissal 

 bristle is. Its separation from breviseta is discussed under that species. 



The known habitats are predominantly dry, e.g. chalk grassland and scrub, coastal 

 dunes, coastal shingle, and suburban grassland. Wetter habitats included a Scottish 

 birch wood. Audcent (1950) recorded it from Bromus sp. but it is more often associated 

 with Arrhenatherum elatius. It has a life history unusual for the genus, adults occurring 

 throughout the year; Ismay (1974) recorded it (as breviseta) at the roots of tussocks 

 of A elatius throughout a complete year though it was most abundant in autumn 

 and winter, and a pair in cop. (in the Natural History Museum) was caught in mid 

 February. Where the collecting method was known, it was usually tussocking or 

 pitfalling but rarely sweeping. It has been observed running and jumping among the 

 deeper layers of tall dune grassland. Although Falk (1991) considered it to be nationally 

 scarce, its secretive behaviour is almost certainly the reason for the few records and 

 is likely to prove widespread. 



As there are many more verified records (*) of subnigra than of breviseta, the former 

 is assumed to be the more frequent of the pair. Therefore, all unchecked records 

 of "breviseta" are included here, though doubtless some have been correctly 

 named by chance: Kent, East Sussex*, Greater London, Surrey*, Hampshire*. 

 Avon, Wiltshire*, Dorset, Oxfordshire, Essex, Suffolk, Norfolk*, Cambridgeshire*. 

 Worcestershire*, Dyfed*, Gwynedd, South Yorkshire, Northumberland* and 

 Highland* (Allen, 1967, 1977; Parmenter, 1960; Collin, 1945; Ismay, 1974). 



Geomyza tripunctata Fallen, 1823. The only other species of Geomyza with the 

 bold wing pattern of tripunctata is majuscula, which lacks the long anepimeral seta 

 and basal wing spot. The colour of the thorax is variable and, although usually 

 blackish, it may be clear orange as it is in most specimens of majuscula. 



Mesnil's combinata also possesses a long anepimeral seta, but the identity of 

 this species is uncertain because the description of the wing in Mesnil (1934) 

 does not tally with the figure that looks remarkably like tripunctata in Balachowskv 

 & Mesnil (1935). 



Geomyza tripunctata is the commonest species of the genus, widespread throughout 

 Britain and found in almost all grassy habitats. It may be found from March to 

 November, with a distinct peak in abundance in April and a less clearly defined one 

 in later summer. Thomas (1938) concluded that it had two generations each year. 

 Larvae have been recorded feeding on a number of common grasses but most often 



