Seq # 603220020

Horisme radicaria (de la Harpe, 1855) Species

Last modified: April 15, 2021, 12:49 p.m.

Probably a rather rare species throughout Belgium, but due to the similarity with Horisme tersata it is unsufficiently known.


Family: Geometridae > Subfamily: Larentiinae > Tribus: Melanthiini > Genus: Horisme > Species: Horisme radicaria
Vernacular names
Tweelingbosrankspanner (NL), L'Horisme jumeau (FR), Flussauen-Waldrebenspanner (DE)
First mention in Belgium
De Prins W. 2016. Catalogus van de Belgische Lepidoptera – Catalogue of the Lepidoptera of Belgium. — Entomobrochure 9: 1–279. On page 176.




With worn individuals it's a good idea to check the genitalia because external characteristics are not enough to be sure at species level. Fresh specimens can be identified by the pale brown ground color, with reddish or warm chocolate brown tinge. Discal spot usually absent. Area between apical streak and costa often pale ochraceous colored.

Museum specimens

No pictures yet!

Specimens in nature


Flight periods

The adults fly in two generations a year with a peak during May and August. They come to light. It has a preference to more termophilous habitats than its sibling species H. tersata, allthough they often fly together.

Observed on

Host plant (genera):

The larva feeds mainly on Clematis vitalba. It hibernates as pupa in a loose cocoon among debris or in the soil.

No pictures yet!