Saturnia spini (Denis & Schiffermüller, 1775)

Host plants:
The caterpillars live mainly on blackthorn (Prunus spinosa), and secondarily according to literature also on other woody Rosaceae like Crataegus, Rosa, Prunus sp. and even other deciduous trees (Alnus, Salix, Ulmus, Rhamnus, etc). I found them in Northern Greece exclusively on Prunus spinosa.

Habitat:
Saturnia spini inhabits drylands with loose shrub associations in continental climates with hot dry summers and cold winters. I found the larvae in May 2011 in Northern Greece (District of Drama) in extensively grazed mosaics of grasslands and blackthorn thickets with marginal low growing bushes at the foot of very dry steppe slopes.

Life cycle:
The pupa hibernates often several times (up to 7 years according to literature) within the cocoon that is constructed in the ground vegetation or under stones. The moths fly from March to early May. The eggs are laid in large batches (on average larger than in the syntopic Saturnia pavionella) usually on stems of the host plant near the ground and unlike S. pavionella densely covered with the wool of the female abdomen.

The hatching caterpillars of a egg batch often devide into several separate groups at the bush or on neighboring bushes and live socially in the younger stages. The caterpillar is found from late April to June or early July, with peak from mid-May to mid-June. The larvae of Saturnia spini are completely black apart from some whitish hair until the penultimate instar. This is contrary to Saturnia pavonia and S. pavoniella in which only the first larval stage is completely black and then a orange or yellow side stripe appears. Only in the final stage the warts get orange, but otherwise the colour remains unchanged black.

Endangerment factors:
Saturnia spini is threatened with extinction in Europe, because the habitats are increasingly restricted. In Northern Greece Saturnia spini is currently apparently known only from the district of Drama. Here the populated blackthorn areas are sandwiched between fields and the steppe slope. The flat part of the larval habitats have a strong risk to be included in the arable land any time.

In Europe following damaging factors are obvious: intensification and expansion of agricultural land (often also EU funded), succession and reforestation after abandonment of extensive transhumance grazing, sprawl by settlements, roads and industrial areas, and climate change with tendency to milder winters. Saturnia spini requires much larger intact areas than its less demanding sibling species!

Remarks:
Saturnia spini still occurs in Europe only in the southeastern part (especially Balkan Peninsula) with a focus in Bulgaria (also smaller sites in Macedonia, Romania, very locally in Northern Greece) and in southern Russia as well as parts of Ukraine. Previously Saturnia spini occurres to the northwest at least to eastern Austria and Slovakia, according to some sources even to Bavaria. These sites are likely to be extinguished all.

Outside Europe, Saturnia spini is found locally in Asia Minor and in the steppes of southern Russia and adjacent areas of Central Asia.