Plant Parasites of Europe

leafminers, galls and fungi

Dialectica scalariella

Dialectica scalariella (Zeller, 1850)

bugloss slender

Dialectica scalariella on Echium vulgare

Echium vulgare, Belgium, prov. Namur, Viroinval, Dourbes, RN “Montange-aux-Buis” © Stéphane Claerebout

Dialectica scalariella on Echium vulgare


Dialectica scalariella on Echium vulgare



Mine upper-surface or, more often, lower-surface. At first a long, narrow, winding epidermal gallery with central, more or less deliquescent, reddish brown frass. The gallery abruptly widens into an elongate blotch that is epidermal at first but soon deeper; the blotch is brown with strikingly white margins. Epidermis finely wrinkled. Lower surface mines strongly contract the leaf (and often there is a mine at either side of the midrib). 2-3 Larvae in a blotch, each with its own initial corridor. Frass in large black grains in a central depot; moreover in the form of very thin threads stuck in a reticulate pattern in the epidermis.

Hering (1957a) states that the pupa lies naked in the mine but pictures on Lepiforum show normal cocoons, with a thin silken wall, not covered by frass. At emergence the pupa works itself for a large part out of the mine.

host plants

Boraginaceae, oligophagous

Anchusa strigosa; Borago; Cynoglossum creticum; Echium aculeatum, candicans, gaditanum, giganteum, nervosum, plantagineum, vulgare; Myosotis latifolia; Symphytum officinale.


Several generations per year.


Not known from the Benelux countries (Fauna Europaea, 2009), but see pictures above.

distribution within Europe

From France to the Iberian Peninsula, Italy and the Balkan Peninsula (Fauna Europaea, 2009). Recently an imago was found in the UK (Agassiz, 2005a).


Gracillaria scalariella.


Introduced in Australië for the biological control of the serious weed Echium plantagineum (“Paterson’s curse”), originating from southern Europe (Kumata & Horak; Sheppard ao; Walsh ao; Wapshere & Kirk).


Agassiz (2005a), Aguiar & Karsholt (2006a), Amsel & Hering (1931a, 1933a), Buszko & Beshkov (2004a), Gebiola, Bernardo, Ribes & Gibson (2015a), Gomboc & Kirichenko (2022a), Hering (1927a, 1932g, 1936b, 1957a), Huertas Dionisio (2002a, 2007a), Huertas Dionisio, Vázquez García & Sánchez Gullón (2013a), Klimesch (1942a, 1950c, 1979a), Kumata & Horak (1997a), Lafranchis (2020c), Lhomme (1934c), Sammut & Mifsud (2008a), Sheppard, Smyth & Swirepik (0000a), Utech (1962a), Walsh, Woods & Dodd (1993a), Wapshere (1980a), Wapshere & Cullen (1984a), Wapshere & Kirk (1977a).

Last modified 6.iv.2024