Alnus glutinosa, Hongarije, Kimle, 5.v.2016 © László Érsek: mine with cocoon

larva in opened cocoon

16.v.2019: larva, dorsal

larva, ventral

pupa in the mine

pupa dorsal

pupa, ventral

Alnus x spaethii, Aalten, 24.v.2002

Alnus glutinosa, Belgium, prov. Antwerp, Balen, Scheps, 14.v.2015 © Carina Van Steenwinkel

same leaf, underside, with oviposition scar

another mine, lighted from behind

larva, ventral view

Alnus incana, Belgium, prov. Namur, Lives, 4.v.2010 © Jean-Yves Baugnée

larva dorsal view

ventral view

Alnus glutinosa, Orvelte, 7.viii.2003

mine

Oviposition in the underside of the midrib or a thick lateral vein; later a large scar is visible there. Initially the larva tunnels in the midrib or vein, that inflates and disfigures somewhat as a result. Then the larva starts a corridor in the leaf blade, quite narrow at first, but strongly widening as the larva approaches the leaf margin or leaf tip. The mine is reddish brown in colour. The mature larva makes itself a dark brown globular cocoon in the mine and pupates there.

Because the mine is made at a time that the leaf still is unfolding, the leaf becomes permanently rumpled. In the course of the summer the mine erodes away, but the combination of the oviposition scar, the swollen midrib and the frayed leave missing a large part of its distal half remains unmistakable.

host plants

Betulaceae, oligophagous

Alnus glutinosa, incana, x pubescens, x spaethii.

phenology

Larvae in May-June (Scherf, 1964a); adults emerge in June (Rheinheimer & Hassler, 2010a).

BENELUX

BE recorded (Curculionidae.be, 2010).

NE recorded (Heijerman, 1993a).

LUX not recorded (Fauna Europaea, 2007).

distribution within Europe

Almost all of Europe, except Ireland, the Iberian Peninsula and the Balkan Peninsula (Fauna Europaea, 2007).

synonyms

Rhynchaenus, Trecticus, testaceus; Rhynchaenus scutellaris (Fabricius, 1801).

notes

According to Hering (1957a) the species is very common throughout Europe, and this is confirmed for the Netherlands by van Frankenhuyzen a.o. (1982a); in my experience during the last decade is rather uncommon in the Netherlands. Also in the UK the species is fairly scarce (Morris, 1993a)
It has long be assumed that O. testaceus and O. calceatus were one and the same species. This has definitely been refuted by Košťál & Caldara.

references

Ahr (1966a), Beiger (1979a), Buhr (1933a, 1964a), Drăghia (1968a), van Frankenhuyzen & Houtman (1972a), van Frankenhuyzen a.o. (1982a), von Frauenfeld (1864a), Hartig (1939a), Heijerman (1993a), Hering (1927b, 1930a, 1957a), Huber (1969a), Kleine (1924/25a), Košťál & Caldara (2013a), Kozlov, van Nieukerken, Zverev & Zvereva (2013a), le Monnier (2003a), Morris (1993a), Rheinheimer & Hassler (2010a), Robbins (1991a), Scherf (1964a), Seidel (1926a), Skala (1936a), Sønderup (1949a), Viramo (1962a, 1970a, 1975a), Vorst (2010a).