Generality
The term processionary is used to indicate different species belonging to the genus Thaumetopoea .
The most known and widespread species in Italy are Thaumetopoea pityocampa (or pine processionary ) and Thaumetopoea processionea (or oak processionary ). In particular, in recent years, the pine processionary has enjoyed considerable media success in Italy, when the excessively hot climate has led to invasions of this animal in many cities.
In this article, therefore, the characteristics and dangers of the pine processionary moth will be analyzed. However, let us remember that the life cycle, the danger to humans and the damage caused to the environment by the oak processionary are completely similar to those caused by the pine processionary.
What is the Processionary?
The processionary is an arthropod belonging to the order of the lepidopterans and to the family of the Notodontidae.
The young specimens of pine processionary occur as larvae between 3 and 4 centimeters long. These larvae are covered with a series of stinging hairs that can be easily detached following contact with the animal, but which can be easily detached and carried by the wind.
Entering the adult phase, however, the processionary undergoes a metamorphosis and becomes a sort of moth, whose life is rather short (a few days).
Life Cycle of the Processionary
The adult specimens of processionary - once the metamorphosis has taken place under the ground - emerge from the ground during the summer months (June - July). Shortly afterwards, the females look for suitable plants to lay their eggs (in the case of the pine processionary, the females will prefer pines; while in the case of the oak processionary, the females will opt for the oaks).
Once the right plant has been identified and the branch chosen, following fertilization, the females lay their eggs in a single cluster that can contain up to 300. Generally, the deposition takes place towards the end of August.
After a period of about four weeks, the eggs hatch giving rise to the processionary larvae. Since birth, these larvae are extremely voracious and are able to feed on the leaves of the plant on which they were born (in the case of pines, they will therefore eat their needles).
In the first periods, the larvae move from branch to branch in the continuous search for new leaves for their nourishment, living inside temporary nests.
As autumn approaches, however, towards the month of October, the young specimens of processionary begin to build the characteristic sericeous nest, in which they will face the winter. The larvae in question, in fact, are animals that do not like cold and very low temperatures can even kill them.
After the coldest months, the larvae begin to resume their activity in the spring and, generally towards the end of April - beginning of May, they descend from the tree in search of the right place for metamorphosis. Once the place has been identified, the larvae are placed at a depth of about 10-15 centimeters and here they will spend a few months in the state of chrysalis . In some cases, however, this state can extend even for 5-7 years. However, once the necessary time has elapsed, the adult specimens will emerge from the ground during the summer months ( flicker period ), thus starting a new cycle.
Did you know that ...
The name of processionary derives from the fact that, when the larvae move in search of leaves to feed on, they arrange themselves in single file, as if they were doing a procession.
Damage and Hazard
Ecological damage caused by the Processionary
As mentioned, the processionary larvae are very voracious from birth and feed on the leaves of the plant on which they were born. Because of this behavior, the processionary causes defoliation of the tree . Not surprisingly, this animal is considered to be the most feared and dangerous defoliator of pines.
Generally, the processionary preferentially attacks the Scots pine and the black pine, but it can also develop on other species of pine and, in urban areas, colonize and also feed on the cedars.
The periods of the year in which the processionary causes the greatest damage to plants are spring (especially in the months of March and April, when the larvae resume their activity) and the beginning of autumn (particularly in October) .
The processionary larvae, feeding on the leaves of the trees, cause a serious weakening in the plants which are thus more easily exposed to the attack of secondary parasites and to the risk of death.
Dangerousness of the Processionary for Man and Animals
The processionary is not only harmful for the plant world, but also and above all for the animal world. The stinging hairs of the processionary, in fact, are easily separated from the back of the animal, either by direct contact, or by indirect contact, transported simply by the wind.
The stinging hairs have a physical conformation that facilitates adherence to skin, mucous membranes and clothing.
Effects induced by contact of stinging hairs with skin and mucous membranes
Skin contact with the processionary hair causes an immediate skin reaction that manifests itself as a painful and itchy rash . Similarly, if the hairs come into contact with the mucous membranes, they trigger an immediate irritative and inflammatory reaction . For example, conjunctivitis occurs in case of eye contact; if then the hairs are able to penetrate deep into the eye, there is the risk of the onset of a serious inflammation which - if left untreated - can even lead to blindness.
Effects induced by ingestion and inhalation of stinging hairs
The symptomatology is complicated and worsens if the stinging hairs of the processionary are ingested or inhaled.
In fact, if swallowed, severe inflammation of the mouth and gastrointestinal mucosa associated with increased salivation, vomiting and abdominal pain will occur.
In the case of inhalation, on the other hand, there will be irritation and inflammation of the respiratory tract with the appearance of sneezing, sore throat, difficulty swallowing and difficulty breathing due to bronchospasm.
The risk of ingesting or inhaling stinging hair is particularly high in animals such as dogs and horses which, by smelling the ground or grazing the grass, may inadvertently inhale / ingest these hairs.
Anaphylactic shock
In particularly sensitive and predisposed individuals, the contact with the hairs of the processionary can cause anaphylactic shock, a very serious allergic reaction that can occur with symptoms such as hives, edema, hypotension, difficulty breathing, dizziness and loss of consciousness. In severe cases, anaphylactic shock can also lead to death.
Effects on dogs
In the case of a processionary ingestion by a dog, the first and obvious symptom is represented by the abundant and sudden salvation, followed by the swelling of the tongue which can even lead to suffocation. Because of the violent inflammation, if it does not intervene promptly, the tissues that make up the tongue may undergo necrosis, with consequent loss of portions of it.
Other symptoms of contact with the processionary are fever, loss of vitality, refusal of food and the appearance of vomiting and hemorrhagic diarrhea.
In case of inhalation, similar phenomena can occur at the level of the nose and its mucosa, associated with breathing difficulties.
Please note
The danger exists only when the processionary is in the larva stage. In fact, the adult specimens are not dangerous for plants, for men and for animals. Similarly, even eggs and chrysalises are completely harmless.
Fight against the Processionary
How to Fight the Processionary
Given the dangers caused by the processionary, both at an ecological level and at the level of human and animal health, it is not surprising that this moth is harshly fought almost everywhere.
The main methods used to eliminate the processionary are:
- Destruction of nests : this method involves the mechanical destruction of the nests through the manual removal of the same from the plant and their subsequent elimination. Naturally, the operator performing the operation must be adequately equipped and must wear appropriate protective clothing. However, this method - however effective - can only be practiced in the winter months (when the larvae have not yet left the nest) and only in the event that intervention is to be made in restricted areas.
- Use of a biological insecticide : the microbiological fight against the processionary is the most used contrast method to eliminate this animal. The biological insecticide used is the bacillus bacillus thuringiensis kurstaki (Btk), a microorganism capable of infecting the processionary larva, damaging its nerve centers and paralyzing it. This insecticide can be diffused by means of an atomizer, or by means of a special helicopter.
- Use of pheromone traps : pheromone traps are used in the summer months when adult specimens emerge from the ground. The purpose of these traps is to confuse males in search of females, in such a way as to avoid contact between the two sexes, thus fertilization and spawning.
- Use of mechanical traps : mechanical traps have been developed rather recently and have the task of stopping the processionary processional larvae, trapping them in a special glue.
- Use of endotherapy: endotherapy is a particular technique which consists in injecting insecticidal substances directly into the vascular system of the plant invaded by the processionary. In this way, the insecticide will enter the animal's body when it eats its leaves.
Processionary in Italy
Between 2016 and 2017 in Italy there was a real alarm "processionary of the pine" due to the multiplication of these moths and for the consequent serious damage to vegetation, but also to humans and animals. In detail, the alarm was particularly felt for the numerous cases of death that occurred in several dogs that came into contact with the larvae of this animal.
The invasion of the processionary, probably, has been favored by the anomalous and excessively hot climate that has hit the peninsula in recent years. We recall, in fact, that processionary larvae generally do not survive excessively low temperatures.
In this regard, we point out that the fight against the processionary in Italy is obligatory by law (DM dated 30/10/2007) in all areas where the presence of the moth seriously threatens the production or survival of the tree population and in all areas in which it can pose a risk to human health and animal health.
Curiosity
The processionary in every regional dialect is called with different names. Among the more particular names (and even a bit bizarre), we recall that of "wrinkle" attributed to it by the Romagnolo dialect and the Venetian dialect and the name "hairy cat", typical of the Tuscan dialect.
Processionary: What to do?
How to behave in case of sighting and / or contact with the Processionary?
Given the potential danger of the processionary for humans and animals, the most inexperienced on the subject could react incorrectly in the event of sighting and / or contact with the animal. Most people, in fact, could be led to kill processionary larvae, perhaps pounding them, without thinking that, on the other hand, such behavior can only make the situation worse, further favoring the dispersion of stinging hairs. In fact, these hairs can remain attached to the sole of the shoe or to the clothes with the risk of coming into contact at a later time and / or with the risk of spreading them at home or elsewhere.
Therefore, below are some useful tips on how to behave in case of sighting and / or contact with processionary larvae:
- In case of sighting of the procession of larvae or even of a single specimen of processionary, DO NOT take any initiative, but immediately notify the competent bodies (municipal authorities, law enforcement, etc.) that will intervene in the most appropriate way to solve the problem .
- In case of contact with the processionary stinging hairs, immediately wash the affected area and go to the doctor or the nearest emergency room.
- In case of ingestion / inhalation of stinging processionary hair by a dog, it is necessary to intervene immediately by washing the areas affected by contact with a solution of water and bicarbonate (wearing latex gloves), in such a way as to remove the stinging substance from the animal. Then immediately take the dog to the vet, where he will receive all the necessary care.
- If processionary larvae are spotted, do NOT eliminate them by do-it-yourself methods with counterproductive results, such as crushing or burning. In fact, burning or trampling on larvae or nests cannot in any way guarantee the removal of hair. Indeed, on the contrary, the hair of the larvae can spread even if the animal is dead, as well as they can potentially spread in the environment even during a possible combustion. Therefore, in the event of a processionary sighting, we renew the invitation to contact the competent bodies.
