Perisomena caesigena
per-ih-soh-MEE-nuh mm see-sih-GEE-nuh
(Kupido, 1825) Saturnia

Perisomena caecigena (male) by Leroy Simon

TAXONOMY:

Superfamily: Bombycoidea, Latreille, 1802
Family: Saturniidae, Boisduval, [1837] 1834
Subfamily: Saturniinae, Boisduval, [1837] 1834
Tribe: Saturniini, Boisduval, [1837] 1834
Genus:Perisomena, Walker, 1855

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DISTRIBUTION:

There is an isolated population of Perisomena caecigena in the Abruzzi Mountains of central Italy. To the east, caesigena (wingspan 62-88mm) flies from southeastern Austria, Slovenia and Hungary through Croatia, Serbia, Albania, the western Ukraine, Romania, Bulgaria and Greece to most of Turkey, Cyprus, and the Caucasus Mountains of the Republic of Georgia, Armenia and Azerbaijan. There is also an isolated population in the mountains of Lebanon.

Perisomena caecigena is celebrated on, what I believe is, a postage stamp from Bulgaria.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

This nocturnal species inhabits dry, shrubby, open woodlands populated with oaks, the favorite larval foodplants. Males start to fly in late September through early November as soon as darkness falls, preferring cool, moist conditions.


Photo (female) by Leroy Simon.


ECLOSION, SCENTING AND MATING:

This species starts to emerge after the onset of cool autumn nights, having spent the late summer as a pupa.

Females, which are less colourful than males, extend a scent gland at the posterior tip of the abdomen to call in the males who use their highly developed antennae to pick up and hone in on the scent plume.

EGGS, LARVAE, COCOONS, AND PUPAE:

In late fall, females lay up to 100 rectangular, 2.5 x 2mm, glossy cream coloured eggs in batches of up to six on the twigs of trees.

A sticky glue keeps the ova affixed to the twigs throughout winter. Eggs hatch the following spring with the onset of warmer weather.

The newly-hatched, 4.5mm long larvae consume part of their eggshells and then wander off some distance to find suitable resting sites among the unfurling spring oak leaves.

Scans by K. Himmelbauer.

Growth is rapid, and larvae shed skins to move into the second instar in roughly one week. Here larva is on Quercus robur.

In addition to oak species, larvae also accept ash, black poplar, white poplar, cherry and pear.

Colouration changes rather dramatically in moving from second to third instar to the right.

The final two instars will reveal larvae with less "hair" on a green body.

As they enter fourth instar and when fully grown, they are similar to the larvae of Saturnia pavonia, being pale green with six small yellowish tubercles per segment, a yellow subspiracular band on the abdominal segments, and long white hairs on the tubercles.



The larvae require hot, dry conditions and reach 60 mm at maturity in the fifth and final instar with little colour change from the fourth instar. There is some colour variation among larval groups with white or a very pale yellow replacing bright yellow tubercles and subspiracle line.

A clear brown pupa with a fine grey pubescence is formed in a 35mm, dark brown, double-walled cocoon.

The inner wall is of a fine mesh, with the outer being coarser. The pupa is clearly visible through both layers of the cocoon which is spun up among twigs and leaves.

The outline of the male antennae are clearly visible in this image courtesy of Tony Pittaway.


Listed below are the primary food plant(s) and alternate food plants listed in Stephen E. Stone's Foodplants of World Saturniidae. It is hoped that this alphabetical listing followed by the common name of the foodplant will prove useful. The list is not exhaustive. Experimenting with closely related foodplants is worthwhile.

Fraxinus
Populus nigra
P. alba
Prunus
Pyrus communis
Quercus robur......
Q. petraea
Q. pubescens
Q. cerris
Quercus nigra
Q. suber
Q. ilex

Ash
Black poplar
White poplar
Cherry
Pear
English oak
Durmast oak
oak
Turkey oak
Water oak
oak
Holly/Holm oak

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