Alnus glutinosa, Nieuwendam: living larva in the mine

Alnus x spaethii, Belgium, prov. Liège, Hermalle-sous-Argenteau © Jean-Yves Baugnée

mine

A large, practically full depth brownish blotch, without a preceding corridor. The mine begins somewhere on the leaf, and expands in all directions, without having much consideration with even major veins. In this respect the mine differs from that of Fenusa dohrnii on the same host plant. Moreover, as a rule there is just one mine per leaf. The full grown larva makes a disc-shaped cocoon within its mine, with a diameter of about 7-9 mm.

Contrary to F. dohrnii the larva is rather vividly pigmented (picture above). Thus can easily be observed without dissecting the mine. Like in almost all sawflies the larva lies belly-up in its mine.

host plants

Betulaceae, monophagous

Alnus cordata, glutinosa, incana, orientalis, x spaethii, subcordata, viridis.

phenology

Larvae from June to October (Buhr, 1941a); hibernation as prepupa in the cocoon (Seidel, 1926b; van Frankenhuyzen & Freriks, 1970c).

BE recorded (Fauna Europaea, 2008).

NE recorded (van Ooststroom, 1976).

LUX recorded (Chevin, Ellis & Schneider, 2011a).

distribution within Europe

From Sweden and Finland to the Iberian Peninsula, Italy and Bulgaria, and from Ireland tot he Ukraine (Fauna Europaea, 2008).

larva

synonyms

Heterotoma, Phyllotoma vagans.
The description of Heterarthrus fruticicolum Ermolenko, 1960 is based on a single specimen, collected from Alnus viridis; nothing is known about a mine. For the moment the status of this species in unknown (Liston, Mutanen & Viitasaari).

parasitoids, predators

Chrysocharis nitidifrons, Chrysocharis purpurea.

notes

The egg is deposited in a cavity that is made with the ovipositor just below the upper epidermis. In the subsequent days the cavity is filled with frass and turns brown (Pieronek, 1966a; van Frankenhuyzen & Freriks, 1970c).

Mines in the older leaves. The leaf tissue of young leaves dies off so soon after being damaged that the larvae would not be able to survive.

Contrary to F dohrnii about 30% of the adults are males; vagans is not parthenogenetic.

references

Ahr (1966a), Altenhofer (2003a), Altenhofer, Hellrigl & Mörl (2001a), Beiger (1979a, 1980a), Beneš (2013a), Beneš & Holuša (2015a), Blank ao (1998a), Buhr (1933a, 1941a, 1964a), Chevin (1984a), Chevin, Ellis & Schneider (2011a), Csóka (2003a), Diškus & Stonis (2012a), Drăghia (1968a, 1972a, 1974a), van Frankenhuyzen & Freriks (1970c), van Frankenhuyzen & Houtman (1972a), van Frankenhuyzen, Houtman & Kabos (1982a), Haris (2009a, 2012a), Hartig (1939a), Hering (1957a), Hoop (1983a), Huber (1969a), Kollár & Hrubík (2009a), Humble (2010a), Liston (1995b, 2011a), Liston & Jacobs (2012a), Liston, Jacobs & Turrisi (2013a), Liston, Mutanen & Viitasaari (2019a), Liston & Späth (2005a), Looney, Smith, Collman, ao (2016a), Lorenz & Kraus (1957a), Maček (1999a, 2012c), Matošević, Pernek, Dubravac & Barić (2009a), Michalska (1972a, 1976a), Nowakowski (1954a), van Ooststroom (1976a), Pieronek (1962a, 1966a), Popescu-Gorj & Drăghia (1968a), Pschorn-Walcher & Altenhofer (2000a), Robbins (1991a), Scobiola-Palade (1974a), Seidel (1926b), Skala (1951a), Skala & Zavřel (1945a), Sønderup (1949a), Stammer (2016a), Starý (1930a), Stritt (1952a), Surányi (1942a), Taeger, Blank & Liston (2006a), Taeger ao (1998a), Viramo (1969a), Wahlgren (1944a, 1951a, 1963a), van Wielink (2020a), Zoerner (1969a, 1970a).