Agromyza nigrescens Hendel, 1920
Geranium pusillum, Amstelveen, Schinkelbos
larva and frass
Geranium robertianum, Blitterswijck; © Wouter Bosgra
Geranium rotundifolium, Spain, Pyrenees, Esterri d’Anneu; © Paul van Wielink
strongly different mine on Geranium columbinum, Belgium, prov. Namur, Sosoye; © Jean-Yves Baugnée
The mine is described by Hering (1957a) as follows: “Upper-surface mine. The start is corridor-like and generally follows the leaf margin. Further on the mine widens considerably, forms a secondary blotch and gets irregular sides that are deeply eaten out. Primary and secondary feeding lines clearly visible. Frass mostly in large clumps. Pupation outside the mine. The mine only rarely occurs inGeranium robertianum; the frass then is fine-grained and the mines are smaller.”
The Dutch material differs considerably from both of these types, in particular because much of the frass is in long threads. Hering didn’t think it impossible the the miners of Geranium robertianum and the other Geranium species might be different species; in this line the Dutch material might form a third species. But it also is possible to suppose an unusually strong effect of the hostplant species upon the mine and the frass pattern.
Larvae in summer (Robbins, 1991a). The larvae of the Dutch material were collected in the first half of September.
BE recorded (prov. Namur, Jean-Yves Baugnée).
NE recorded (Ellis, 2007: Amstelveen).
LUX not recorded (Fauna Europaea (2007).
distribution within Europe
Europe west of the line Finland – Poland – Serbia, but not (yet?) known from Ireland (Fauna Europaea (2007).
Agromyza microchaeta Hendel, 1920, A. heringi de Meijere, 1925, A. oycoviensis Beiger, 1960.
While Hering (1957a( writes that the species is rare on G. robertianum, Robbins (1991a) states that in the UK robertianum is the only hostplant. This matches with Hering’s hunch that nigrescens may be a mix of two species.
Beiger (1960a, 1970a, 1972e), Buhr (1930a, 1932a, 1941a,b, 1964a), Černý (2004a, 2011A), Černý & Merz (2006a, 2007a), Černý & Vála (1999a), Ci̇velek, Çikman & Dursun (2008a), Gil Ortiz (2009a), Hartig (1939a), Hering (1927a, 1932e, 1955b, 1957a, 1967a), Huber (1969a), Maček (1999a), Masetti, Lanzoni, Burgio & Süss (2004a), de Meijere (1925a), Michalska (1970a), Ostrauskas, Pakalniškis & Taluntyte (2003a), Pakalniškis (1993a), Papp & Černý (2015a), Robbins (1991a), Rydén (1956a), Skala (1951a), Skala & Zavřel (1945a), Sønderup (1949a), Spencer (1953a, 1957f, 1972a,b, 1973c, 1976a), Starý (1930a), Surányi (1942a), von Tschirnhaus (1999a), Withers (2007a), Zlobin (1986b).