Seq # 601130010

Theria primaria (Haworth, 1809) Species

Last modified: Jan. 21, 2023, 11:30 a.m.

A not so rare and widespread species in the southern part of Belgium. In the northern part of the country it is very rare with some scattered isolated populations.


Family: Geometridae > Subfamily: Ennominae > Tribus: Theriini > Genus: Theria > Species: Theria primaria
Vernacular names
Meidoornspanner, Sleedoornspanner (NL), Early Moth (EN), La Phalène précoce (FR), Früher Schlehenbusch-Winterspanner (DE)
First mention in Belgium
Hecq J. 1979. Nouvelle espèce de Géometride pour la Belgique, Theria primaria Haw. — Lambillionea 79: 2. On page 2.




Wingspan, males have wings 27–35 mm., females are micropterous 7–8 mm.
Forewing male russet-tinged brown, finely streaked with lighter hue. Transverse lines and discal spot moderately visible, widely spaced at inner margin. Hindwing brownish white with distinct discal spot. General appearance rather dull.
Female with forewing stumps (about 3/5 lenght of abdomen) crossed by a rather broad brownish band on greyish brown background.

Museum specimens

Specimens in nature



When fresh greenish color, later brownish.


Usually found in May and June. Caterpillars are greenish white, dark green or dark brown in color. The green-white caterpillars have an unsigned form with only a number of white lines, of which the subdorsal are the most striking. The other two color forms have square dark spots on their backs. Cannot be distinguished from Theria rupicapraria with certainty.


Hibernates as a pupa in litter on the ground or underground.
The adults come to light.

No pictures yet!

Flight periods

The adults fly depending on mild conditions onwards from late December towards March and might be overlooked in some areas because of the early flight period. This species seems to fly a little earlier than Theria rupicapraria.

Observed on

Host plant (species):
Prunus spinosa
Host plant (genera):

The larva lives mainly on Prunus spinosa and on Crataegus.

No pictures yet!