Processionary Caterpillar
Thaumetopoea pityocampa 
Well its that time of year again when we with Pine trees, Cats and Dogs have to be on the look out for these very dangerous little critters, that can kill a pet dog or cat within hours.  The pine processionary caterpillar is the best known of all the processionaries, studied as early as 1736 by Raumier and later by Fabre (1898) whose essay “ The life of the caterpillar” is among the classics of popular entomological literature.  The insect is found in the warmer regions of southern Europe, the Near East, and North Africa.  It is the habit of the caterpillars to move over the ground in long head-to-tail processions and to sting with urticating hairs anyone who attempts to molest them that has brought the caterpillars to the attention of the public.  It is also one of the most destructive of forest insects, capable of defoliating vast tracts of pines during its episodic population surges.  Of interest here, however, is the fact that is among the most social of caterpillars.  Sibling groups stay together throughout the larvae stage, often pupating side by side at sites they reach by forming long, over-the-ground, head-to-tail processions. The insect is active only during the colder times of the year, spending the warm summer months as a pupa buried in the ground.  The moths begin to emerge from the soil in August and shortly thereafter mate and seek out pine trees where they place their eggs.  Anti-Predator Defence The caterpillars of the pine processionary are highly urticating in the third and subsequent  instars.  Contact with the hairs causes skin rashes and eye irritations. Susceptible individuals may also develop an allergic response to a protein associated with the hairs of the caterpillar. 
The Nest Of the Pine Processionary Caterpillar in a Pine Tree
“ The life of the caterpillar”
Fabre (1898)

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