What are processionary moths

With the arrival of spring there is a good chance of encountering the processionary moth (Thaumetopoea pityocampa). These are curious and apparently harmless caterpillars that take their name from their peculiar habit of moving along the ground in a line, forming a kind of "procession".

Harmless adults, terrible caterpillars

These animals — insects of the order Lepidoptera — become harmless moths in adulthood, but in their larval stage they can be dangerous to humans and even lethal to animals, particularly to dogs, which have a habit of sniffing the ground and biting at anything that moves.

The processionary moth's hairs are the danger

The danger comes from the urticating hairs that cover the processionary moth's body. These hairs are released into the air when the caterpillar feels threatened, and their barbed shape allows them to latch onto the victim, causing reactions in the skin, mucous membranes, eyes and respiratory tract.

Where processionary moths nest

Processionary moths nest mainly on pine and oak trees, and are extremely damaging to the plants that "host" them. The period of greatest risk of contact with processionary moths begins in March, the phase when the larvae typically leave their nests, and lasts at least until the end of April.

Effects of the processionary moth on dogs: the symptoms

If your dog were to "taste" a processionary moth caterpillar, you would notice very quickly — the symptoms are indeed fairly immediate. The first is sudden and intense salivation, which is often followed by vomiting; the tongue then swells considerably and a process of necrosis begins in the area that came into contact with the caterpillar, resulting in the loss of portions of the tongue. The dog also shows clear signs of weakness, refuses food and may develop a fever.

The consequences of processionary moth contact

The consequences could be fatal for the animal, particularly if contact was prolonged, so it is essential to act as quickly as possible. It is clearly important to take the dog to the vet as soon as possible, but there is a first-aid measure that can prove very useful.

What to do if your dog licks a processionary moth caterpillar

You should quickly remove any remaining hairs by washing the dog's mouth with a generous amount of water and bicarbonate of soda solution (it is advisable to wear latex gloves to avoid coming into contact with the urticating hairs yourself).

Keeping away from processionary moth habitats

At this time of year, therefore, wherever possible it is advisable to keep away from pine and oak trees when out for walks, bearing in mind that processionary moths tend to target young trees. If you let your dog roam freely in a park without keeping constant watch over it, another preventive measure (however unwelcome to your pet) is to have it wear a muzzle.

Processionary moth nest: pest control is compulsory

Pest control against processionary moth caterpillars has been compulsory in Italy since 2008, when a ministerial decree came into force establishing that "the control of the pine processionary moth is compulsory in areas where the regional bodies identified for the purposes of Legislative Decree of 19 August 2005, no. 214, with territorial jurisdiction, have determined that the presence of the insect poses a serious threat to the health of people or animals or to the survival of the tree population". Responsibility for removing processionary moth nests lies with the Forestry Corps or professional pest-control operators. If the infested plant is on private property, the cost of pest control is borne by the landowner.

The effects of processionary moths on humans

Processionary moth caterpillars are also a danger to humans, as their urticating hairs can easily become airborne. If the hairs come into contact with the skin, they can trigger skin reactions and allergic reactions, while if inhaled they can cause localised inflammatory reactions, which are particularly dangerous for more sensitive individuals. In the event of contact, it is advisable to wash the affected areas thoroughly to remove the hairs and to consult a doctor.

Pest control methods

Several techniques exist for eradicating processionary moth caterpillars, ranging from mechanical control to the use of biological insecticides.

Mechanical control

This involves the manual removal of processionary moth nests by cutting off the infested ends of the plant. This procedure is usually carried out during winter, before the larvae have left the nest. It is an effective technique but very time-consuming, and is therefore recommended only when the area to be treated is limited.

Microbiological control

This method is widely used and involves the application of a biological insecticide based on Bacillus thuringiensis kurstaki (Btk). This insecticide, which is harmless to people and dogs, acts rapidly by blocking the trophic activity of the larvae. It can be distributed by aerial application or by means of an atomiser.

Pheromone traps

Pheromone traps "simulate" the substances released by the female processionary moth to attract males during the mating period. By doing so, the likelihood of males and females meeting and reproducing is reduced. The best time to set these traps is the month of June.