Parallelomma vittatum
The separation from P. paridis is discussed under that species. Wing length: ♂ 3.5 - 4.0 - 4.4 mm (3); ♀ 3.9 - 4.1 - 4.6 mm (8).
Nelson (1990)[1] reared this fly from larvae mines in the leaves of Heath-spotted Orchid (Dactylorchis maculatum ssp. ericatorum). Bland (1975)[2] reports rearing specimens (det. V.R.Vockeroth) from a leaf mine in Broad-leaved Helleborine, Epipactis helleborine found in the Ordesa Valley (presumably, Spain?). Some of the older literature mentions many other plants (including orchid genera Ophyra, Listera and Orchis, and also non-orchids such as Paris and Polygonatum), but given the confusion over nomenclature, these records need treating with care. Nelson (1990)[1] reports the average number of eggs laid on a leaf was 2.1 and larval development was rapid taking only 9 days. Six pupae took most of the year to develop whilst five hatched in 26 days, giving rise to a second generation. This fits with field records of adults which extend from May until September and show that the species is at least partially bivoltine. Nelson reports that a male caught and fed on a psocid and both sexes fed from a squashed raspberry, but none lived longer than 10 days.
References
- , 1990. Observations on the biology and status of British dung-flies of the genus Parallelomma Becker (Dipt., Scathophagidae). Entomologist's monthly Magazine, 126, pp.187-189.
- , 1975. Parrallellomma vittatum (Meigen) (Dipt., Scatophagidae) in Spain. Entomologist's Record and Journal of Variation, 87, pp.124-125.
The available records suggest that this is less scarce than P. paridis with widely scattered records, mostly from Scotland, but also England and Wales.
World distribution: Palaearctic: Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Ireland, Lithuania, Netherlands, Norway, Poland, Slovakia, Spain, Sweden, Switzerland; Russia: northern European regions; Nearctic: Canada, USA.