How to eliminate the pine processionary: The 6 best methods

Posted By: Manuel Gaviño In: Plant care Comment: 0 Hit: 5003

Do you have a plague of processionary and don't know how to eliminate it? Discover the 6 most used methods

It never fails.

Spring is approaching and activity begins at the top of the pines.

The bolsones, those white cotton-like bags that can be seen among the branches, open up. And from them begin to emerge, in single file and close together, a row of orange caterpillars.

The processionary.

A known enemy of those of us who love gardening and of those who have pine trees close to home.

And it is that this caterpillar is not only a voracious eater, which can wreak havoc both in the pines and in other plants that are nearby.

In addition it is also a risk for both animals and people (especially for children).

If this is your case, don't worry.

In this post we are going to teach you several of the most used methods to eliminate the pine processionary moth and prevent it from spreading through your garden.

But first we must understand why it is so dangerous.

Why it is so important to eliminate the pine processionary moth: possible risks of this caterpillar

Although we only remember it in spring, the processionary moth spends many months with us, hidden high up in the pines.

The moth (which is the adult form of the caterpillar) lays its eggs in late summer. Once they hatch, the larvae begin to feed on the leaves around them and form their nests, those characteristic cottony-looking pockets that are so recognizable.

Although they don't look like it on the outside, inside each of these bags. It can contain hundreds of larvae.

Then, between February and March (when temperatures rise), the larvae file down to the ground to find a place to bury themselves, until they emerge towards the end of summer transformed into moths.

But it is son this path to the ground when they are most dangerous.

What are the dangers of the pine processionary moth?

It depends.

If we talk about the danger that these insects pose to people and animals, the reality is that the danger is not in the larvae themselves (they are not poisonous or bite).

The real problem are the stinging hairs that cover them, and that can cause:

Hives and skin rashes (lasting a few days to several weeks).
Respiratory problems if we inhale them.
Eye irritation.

Even if an animal bites or swallows them, it can endanger their health (it is very important that you take this into account if you have dogs or cats). They can also pose a risk to younger children, who might put them in their mouths out of curiosity.

But what about the pines?

Well, while are growing, caterpillars are very voracious insects.

A colony of processionary moths can devour all the leaves on a pine tree (at which point they will move on to others) and eventually kill the host tree.

That is why it is highly recommended to remove them. And if we do it before they go down to the ground, the better.

From when can you combat the pine processionary moth?

This will depend a lot on the method we use and the means we have available.

If we opt for:

Remove processionary nests.
Eliminate the processionaries on the ground (because we do not have the necessary materials to remove the nests).

These tasks will take place between late winter and early spring, depending on when these caterpillars begin to emerge from their nests.

Be careful because the ideal time to eliminate the processionary caterpillar is not spring, as many believe, but rather autumn.

When the eggs have just hatched and the pockets are forming, the caterpillars have not yet developed their stinging hairs. And that makes the process of removing them much safer.

Even so, several to see methods to combat them and end them at different times of the year.

The 7 most used methods to exterminate processionary moths (+1 that we recommend you avoid)

1. Elimination of the processionary moth with endotherapy

A technique that we have already discussed in a previous post

Endotherapy is a phytosanitary treatment with which an insecticide is inserted into the pine trunk.

In this way, the phytosanitary product infiltrates the sap and circulates throughout the tree until it reaches the leaves. When the caterpillars start to eat them, they die. In addition, in the process the tree does not suffer any damage.

This treatment is carried out in autumn, when the eggs have just hatched. In this way, we prevent the caterpillars from developing their dangerous stinging hairs and from killing the tree.

So this is one of the most effective and safe methods to eliminate the processionary.

2. Biological anti-wrinkle

Another option is to use a bacterium called Bacillus thuringiensis, a mode of "natural insecticide".

This bacterium is administered in the form of powders that are applied to the affected plants.By eating the leaves, the caterpillars also ingest the bacteria.

As with endotherapy, this method does not carry any risk for the plant or for animals or people.

3. Manual removal of nests

If we have not been able to kill the processionary with some of the previous methods, another possibility if the nests are at an easy height to reach is to lower them directly.

But be careful, because this carries a risk.

If you do it between winter and spring, the larvae will have fully developed and will be covered by their stinging hairs.

In this case, you should use long gloves and all the necessary protection to prevent the hairs from rubbing against your arms.

In addition, once the nest has been taken down, you must burn it immediately in a suitable container. This will not only kill the larvae, but also the stinging hairs that might otherwise end up floating in the air.

To eliminate nests, it is better to do it in the central hours of the day, when the larvae are inactive.

A trick that also works to avoid hives is to wet the pockets before cutting them.

4. Break the bags

This is a practice similar to the previous one, but with fewer risks.

The idea is to open the bags to leave the caterpillars exposed to the outside. These insects are sensitive to cold so if you do it during the winter,when night temperatures are still low, the cold outside will kill the larvae.

Of course, remember to break them close to the night, or else the larvae will have time to rebuild the bag.

5. Put up physical barriers

It consists of putting a plastic barrier surrounding the foot of the pine tree where the caterpillars have been installed.

When they come down from the tree, the caterpillars are unable to overcome this barrier and end up dying.

This method can be very effective if you have few trees affected by the processionary moth. If you have a large piece of land and a large plague, it will be difficult for you to put it into practice.

6. Pheromone traps

This method works long term.

The traps contain synthetic pheromones similar to those given off by female caterpillars. Approaching her, the males find themselves caught in the traps.

In this way, we only end with a part of the plague, but we break the reproduction cycle (by the end of the following summer there will be no male moths to mate with the females).

7. Natural enemies of the processionary

There are certain animals that feed on the processionary caterpillar. And if we manage to attract them to our garden, they will help us control the presence of this dangerous insect.

Specifically, there are certain birds that are natural predators of the processionary, such as:

The great tit.
The common tit.
The common chaffinch
The common blackbird.
The black starling.

In this post on our blog, we give you several tips to attract birds to your garden.

This method is more complex to apply, but it can serve as a complement to others that we have seen on this list.

8. Other home methods to eliminate the processionary

Finally, we include some home methods that some people use to eliminate these pests.

They are the following:

Soapy water: it is about spraying a mixture of soapy water on the nests twice a day, until killing the caterpillars.
Homemade insecticide with tobacco: This method consists of mixing cigarette ashes with water to make a kind of homemade insecticide, and spraying them on the affected plants. The problem is that an excess of nicotine can be harmful to the plant itself.

Regarding these methods, our advice is clear: avoid them at all costs.

To begin with, you are not sure that they are really effective. Not only that, but in the worst case you could even end up damaging your plants (also, remember that careless handling of nests is dangerous).

If you need to get rid of a processionary infestation, our recommendation is that you opt for one of the methods on the list and, if you can, that you go to a professional to avoid risks.

You already know how you can get rid of the processionaries

As you have seen, the bad reputation of the processionary caterpillar is more than justified.

In addition to being harmful to plants, it can also be dangerous for us and our family (animals included).

Hence, our recommendation is that, if you suffer from this plague, you eliminate it as soon as possible.

At Viveros González we know this well, and for this reason one of the most requested jobs between autumn (during the time of endotherapy)and the spring It is precisely that we take care of eliminating these nests.