The processionary caterpillar in Portugal is the pine processionary Thaumetopoea pityocampa. It’s a defoliating insect, which can parasitize pines and cedars. It’s called the processionary because of the way the stage 5 larvae move when descending from their nests to burrow in the ground to pupate. They move in a line resembling a procession.
Growth Stages
The caterpillars go through 5 growth stages. From the 3rd stage onwards they have urticating hairs that cause allergies on the skin, eyes and respiratory tracts. These allergies are always very unpleasant and can have severe consequences. The severity will depend on the sensitivity of the person or animal affected. So be careful and mindful if you have inquisitive children or animals with you when you’re on that walk!
Biological cycle
Its life cycle completes in one year and consists of two stages: the adult stage formed by egg-laying moths which can be seen on the tops of pine trees, and the pupal stage which is underground.
Young caterpillars live in temporary nests that are abandoned until the formation of definitive nests (winter nests), where they protect themselves from low temperatures. These nests have silk-like pockets appearance, easily identifiable in pine tree tops, where the caterpillars remain in active growth.
Depending on weather conditions, amongst other factors, usually between January and April, the caterpillars descend from the pine trees forming the so-called processions.
The caterpillars have their body divided into small segments, each of which has hundreds of orange-coloured stinging hairs that are shed and spread through the air as the caterpillar moves around. It is these hairs that come into contact with the skin, mucous membranes and eyes that are responsible for allergic reactions in people and animals.
What are the symptoms?
The signs and symptoms resulting from contact with urticating hairs are an allergic reaction, the severity of which depends on the intensity of exposure and individual sensitivity:
Urticarial reaction: skin irritation with itching, burning, erythema (red skin) and oedema (swelling). Skin lesions have maculopapular features and may be accompanied by vesicles.
Eye irritation: similar to conjunctivitis with reddened eyes, itching and oedema.
Inhalation of the hairs may trigger coughing and dyspnoea (breathing difficulty) of varying severity.
Symptoms may appear a few minutes or hours after contact and persist for several hours or days.
What should you do in the event of contact
- Wash the skin/ eye with running water;
- Remove any urticating hairs that may have adhered to the skin (e.g. with an adhesive patch);
- remove clothing
- local application of moisturising cream;
- Give an antihistamine orally.
In the case of eye contact, an ophthalmologist should always be consulted.
In the event of a more intense allergic reaction, you should seek emergency medical attention.
If necessary, call 112.
In any case, you can always contact the Poisons Information Centre – (00351) 800 250 250.
Note: Watch your Animals!
Animals are equally sensitive to contact with caterpillars, and the recommended procedure is identical to that described above. It is advisable to have them examined by a vet, particularly in the case of cats and dogs.
Disclaimer: I’m not a medical professional. Please contact a medical professional in case of a medical emergency.
Emergency phone numbers:
112 (National Emergency Number)
Poisons Information Centre – (00351) 800 250 250
National Health Service (SNS 24 ) – (00351) 808 24 24 24
Source: https://www.icnf.pt/florestas/fitossanidade/agentesbioticosnocivos/processionaria
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