Processionary Caterpillars

[Robano]

Now the Mantis has gone and we have found processionary caterpillar nests in a pine tree. Have removed the two obvious ones but now see there are loads more much higher up in the tree.

Anyone know how to get rid of them? Also when the become a danger?

Steve

[wildside]

Hi,

The processionary moth lays eggs at the top of various pine tree species... Once hatched the small first instar caterpillars congregate together and as the weather gets colder they build the nest that you see in the trees... The nests are normally on south facing side of the tree so the caterpillars get as much sun as as possible.. This is for warmth which aids in the digestion of pine needles...The community of caterpillars come out at night to feast on pine needles.

The caterpillars shed their skins seven times and each stage is called an "instar" The seventh stage is when they leave the trees...

The caterpillars are at their most dangerous after they leave the trees to find a place to pupate...This is when you find them on the ground in the long processions... They are looking for soft earth in which to burrow where they will chrysalis untill the time is right to pupate into moths where the cycle will begin again...

If your infested tree is on an urbanisation then tell whoever is in charge about the problem... The council has an obligation to remove them...

Be VERY careful if you remove them yourself.... This is really a job for an experienced person who has worked with this type of infestation before...

Never burn the nests that you cut off the tree. The irritant hairs will be airborne and you could breath them in...

In the past I have dug a large hole and cut the nests from the tree using long loppers... I always wear a breathing mask and full gloves and covered arms and legs...Place as many nests as you can in the hole and cover it with earth...

You could also try using a kids water pistol super soaker filled with an insecticide and spray the higher nests carefully... (I normally wouldn't suggest chemicals but garden centres sell an insecticide for processionaria). Try to just spray the nest and nothing else... Insecticides kill beneficial insects as well... Do some target practise first... Or call a gardener who may have a chemical sprayer with an extended lance to treat pests in tall trees..

Anyone who has had a re action from these caterpillars will tell you how painful it is...

Keep your pets away from the caterpillars and in pinewoods at this time of year keep your dog on a lead...You will regret it if beloved fido finds some on the ground and gets one in his mouth...

Hope that helps...

Clive

PS Note to moderator... This processionary subject should really be split off to its own topic as it is nothing to do with empusa pennata mantis...

[oliveview01]

Our neighbours have the processionary caterpillars in their pine trees. The first year here I reacted badly to the caterpillars, my neck and upper chest was really bad with the itching! I keep away from the trees whilel they have the insects in them. My neighbour sprays them as they come out of the tree with ´strong water´ I think it might be a bleach solution.

[julian]

it´s acid !!

[dido72]

Not all councils will come out to remove them as they don't consider them a threat. Where I used to live in Frigiliana there was a square a the front of my house with a huge pine tree in it, it had about 15 nests in it, luckily we moved house just before they came out but our neighbours said that all the Spanish including the kids came out and stamped all over them!!!

My friends son got one hair on his face and it blew up to twice it's size, he looked like the elephant man (he is 3 and usually very beautiful)!

[wildside]

Not all councils will come out to remove them as they don't consider them a threat

After reporting to the local council with no result contact the Guardia Civil SEPRONA unit.... And tell them that the council refuses to act on a catalogued and recognised invasive species causing danger to the public...

It is the voice of the concerned individual shouting loudest that will be heard... And SEPRONA will listen.....They have to by law...

It is pointless to wait until the 5th instar... Its a classic case of closing the stable door after the horse has bolted.... Get them when they are in their 2nd to 5th instar... They are weaker at that point, all in one small area during the day (the nest) and so killing them is easier....I think I might go into business dealing with these things....I'll finally be rich..

Clive...

[wildside]

HI,

I wrote this a while ago for a local paper... Cant find it on their web site now but here is the article

Clive

The pine processionary caterpillar and its life cycle

When living in Spain and thinking about creepy crawlies in general many people often wonder about the dangers of scorpions, spiders and venomous snakes and will not be aware that they are much more likely to endanger themselves and their pets by getting too close to an innocent looking line of caterpillars that can be found at this time of year (spring) crossing a road or footpath.

The pine processionary caterpillar (Thaumetopoea pityocampa) is known as procesionaria del pino in Spanish and during late winter/early spring they will be coming out of the trees and forming conspicuous snakelike lines as they traverse the ground searching for soft soil to burrow into. They will not be far from a pine tree, but that does not mean that you will only see them in large pine woods, they are just as likely to be found in urbanisations and road side plantings wherever pine trees are present.

There are several stages within their lifecycle but they are only dangerous to people and pets during the caterpillar phase. In the adult phase they are a simple and unremarkable, short lived moth which emerges in the summer and flies at night. The male moth is attracted to the female moth by pheromones that she emits. They will mate and a single female can then lay up to 300 tiny eggs which she attaches in a mass to a pine needle. Around one month later these eggs hatch into minute caterpillars. These larvae have 5 growth stages that are called “instars”. They grow quickly in body size, moult their skin and that denotes the start of the next instar.

These social caterpillars living in family communities eat pine needles by night and sleep in little temporary silk nests by day. At this point they are nomadic and the nests are not really visible. However at the third instar (moult) the siblings build a permanent white silky nest on the tip of a pine branch. These appear during the winter as white cotton or candyfloss like structures and a single pine tree may have many. If there are half a dozen or more in the top of a tree they can easily strip the leaves with their nightly foraging, possibly clearing all greenery off some branches and in many cases damaging the tree badly. By feeding under the cover of darkness they avoid attack by birds and predatory wasps. At dusk the caterpillars leave their communal nest in search of food, there is no single entrance hole, they simply push through the silk layers and once onto a branch they will leave a scent trail to help themselves find their way back before the morning light arrives.

This period of night time eating occurs during the winter months and whilst low temperatures may slow them down, it would need to be below minus 16 degrees Celsius to kill them. The silken homes are carefully positioned to take advantage of the sun’s heat and this warmth is absorbed into the nest thereby aiding the resting caterpillars to digest their previous nights meal. Also the fact that there can be up to 300 caterpillars in a nest helps to keep the nest warmer by as much as a degree or two than the outside temperature.




During the stage of the 5th and last instar the nest will be looking dirty as it has over wintered and excrement has collected at its base. Generally this stage happens around February and March but depending on spring temperatures can be in April as well. This is the time for them to leave the nest in preparation for the next part of their lifecycle. And it is this point when most people and pets come into contact with the caterpillars, sometimes with very painful consequences. The colony follows a leader, nose to tail, in a long procession. These processions can vary greatly in length, depending on how many have survived to this final caterpillar stage and whether they have been disturbed. 60 or so caterpillars each about 4cm long in a chain can be an impressive sight and if seen along a road may be mistaken for a snake. While searching out a pupation site, they may travel a distance of 30 or so metres to find soft soil to burrow into.

Once underground they change into pupae and during this part of their lives they look nothing like a caterpillar at all, now they are covered in a tubular brown protective casing and they will lay dormant until the summer months. They have stored nutrients in their bodies on which they will survive the pupal stage of development. If the weather conditions are not favourable, they may remain underground until the following year. This is why some years seem to have many more visible nests than others, it may literally be because two years of moths (this years and last years) emerged at the same time.

And so on to the dangers involved, the best advice is to avoid these innocent looking creatures at all costs. The caterpillars are covered in tiny barbed hairs which are their defence mechanism. These hairs are often being shed and so can be airborne around infested pine trees, on the branches where they have travelled and also left in the line of the migrating procession.

When humans and our pets come into contact with these hairs, they can cause reactions ranging from mild inflammation and irritation to severe anaphylactic shock. The worst problems occur if you make contact with the caterpillar directly and ingest the hairs, either by picking it up, stepping on it or moving them in some manner. Once on your skin a rash soon forms which can be incredibly itchy. Medical advice should be sought if you are unfortunate enough to experience this. The rash can be painful, very itchy and lasts for as much as three weeks.

Moving the caterpillars, their nests, or even the branches that they have walked along, may release these hairs into the air where they can be inhaled or come to rest unnoticed on clothing. The nest material that remains on the tree after the caterpillars have left will still contain the “urticating” hairs. (The word “Urtica” is Latin for Nettle, a plant that has barbed hairs which cause a rash). Even burning infected pine branches should be avoided as the hairs can be pushed into the air and fall anywhere or be inhaled.



Veterinary services have many emergency calls at the time when the caterpillars are migrating to the ground as inquisitive dogs can get too close to the intriguing procession and may pick up the hairs onto their paws, these irritate and so they lick them. Once the hairs are on the lips/tongue it will induce itching, swelling and possibly vomiting. Look out for the symptoms of: small white spots in the mouth and on tongue, excessive drooling and chomping. In some cases partial amputation of the tongue is often the only course of action.

These defoliating pests, which can attack all types of pine trees, are found in warmer parts of Southern Europe, North Africa and across to the Near East. Their numbers have increased partly due to large plantations of pine trees in the Mediterranean areas. This facilitates their ability to multiply successfully. Milder winters, as have been occurring recently, are allowing these insects to expand into new areas, both into more northern latitudes and higher elevations.

Their favored food tree is Black pine (Pinus nigra) followed by Canary Island pine (Pinus canariensis), Scots Pine (Pinus sylvestris), Maritime Pine (Pinus pinaster), Aleppo Pine (Pinus halepensis) and Stone Pine (Pinus pinea).

Whilst there has been some work done on pheromone traps/mating disruption systems to try to halt the spread of these pests, at present there seems to be no testing being carried out in Andalucia. Another form of control that is regularly used in Spain is the indiscriminate aerial spraying of pine forests with lethal mixes of insecticides and diesel oil as a fixative to stick the liquid to the pine needles. Of course this kind of treatment kills all insects and also in many cases the birds that eat the insects. Having witnessed this first hand and having been sprayed by an aeroplane with this mixture I have to say that whilst the pine processionary caterpillar is a serious pest this kind of treatment is simply not acceptable.

If you are aware of the presence of processionary caterpillars in your area then contact your local town hall and ask them what their policy is for control and eradication. In large forests this is a complicated problem to solve but in individual and small plantations on urbanisations or in towns there should be an eradication system in place. If not, ask why not.

Under no circumstances should you try to handle the caterpillars, cut down the nests or try to burn them.

You can read more about pine processionary caterpillars and see more images and discussions at the iberianature forum.
http://www.iberianatureforum.com/index.php?topic=64.0

[Jool]

They are VERY early this year......we have some nests in our garden to get rid of, always the very same tree and no other......

[wildside]

Hi Jool and all

Interesting you say that they are early, normally the 5th instar is reached around the last weeks of January and at this point the caterpillars leave the tree to find a pupating site... The ones I saw last week in the Sierra de las Nieves in Malaga province were at the 4th instar so that puts them about normal for the time of year... I would expect to to them on the ground in early Feb and through to March...

Of course, these creatures are dependant on the temperatures and weather so the time-scale of their development will fluctuate... Have you noticed how they make the nests on the sunny side of the tree? They need the warmth in order to digest the pine needles...

Do you know the species of your tree that they prefer Jool? Maybe post a picture of it?

Clive

[Jool]

I´ll try and find out re our trees, all our nests cut down and burned now, but in a local town a dog died from these caterpillars very recently......so they definitely are on the move very early.........

[Robano]

When these little beasts come out and process - do they take long about it? In other words once you see them do you have to keep pets away for a long time or is it all over in a few days.
Thanks
Steve

[wildside]

Hi,

The Caterpillars instinct is to "process" to a soft area of ground as quickly as possible so that they can burrow into it ans pupate... So colony for colony the process is quite quick.. From leaving the tree I would guess that they are only on the ground for 24 to 48 hours before they find a place...

The ground walking season is extended of course because all the caterpillars on hundreds, sometimes thousands of trees hatched at different times depending on when the moths laid the eggs back in the previous August...

You might have 30 nests on one tree slightly staggered in growth rates and in a pine forest the season for them to leave the trees is late January to March...(Depending on temperatures through the winter.)

So to answer your question, Robano, each nest that leaves the tree is over in days but the whole population takes many weeks (months) to disperse...

Clive

[Robano]

Thanks Clive

We have five trees but I can only see the nests in one. They seem small and there seems to be only maybe 4 or 5 nests - but they may be obscured.

Its cats we have and I understand they are likley to be more careful than dogs but the hairs released can still affect them. I will give thjem a talking to.

Cheers
Steve

[wildside]

Hi Steve,

If you can get hold of a kids water pistol thing like a "Super Soaker" or anything else that can spray long distance then a mixture of 50 percent bleach and 50 percent water aimed at the nest has been proven to "melt" the nests and kill the caterpillars..

This would be when the nests are small and not when the caterpillars are already at the 4th or 5th instar...

Each nest can hold up to 300 caterpillars so if they get to the ground from your tree and all pupate to moths each female moth lays in batches of 300 eggs... I have no idea how many batches a female lays..

5 nests times 300 caterpillars equals 1500 moths times 300 eggs equals 450,000 new caterpillars... Ok so not all are female moths that pupate.... Lets say 50 percent are male? Still at two hundred and twenty five thousand new caterpillars from just 5 nests....Predators might take care of another 60 percent but what if the female lays five or 6 batches of eggs?

My figures are not scientific but you get the picture why it is important to destroy even 1 nest on a pine tree in a garden..

[Jool]

Yes you would be amazed how many caterpillars are in one nest.........even a small one. You also need to consider that they only walk in a line so if one goes the long way round the whole procession will. I once saw a line of them walking down a house wall, along the windowsill then across a terrace to get to the ground (not my own house) and it went on for a good length......about 25 metres......

The other reason to destroy the nests is because the female moths like to return to the tree where they grew up and breed there so you simply have a recurring problem. So far we have only ever had nests in one of our trees.........we opt for the cut the branch down, put nest in a bag, douse with petrol until it is soaked and then set fire to it approach.......others spray the nest with hairspray first to stop loose hairs fleeing in the air.......

If you find it hard to see the nests, which is not always easy in the bright sunlight, then look for areas where there are brown needles......or branches less green in colour....

[avellana]

Just thought it would be sensible to bring this posting to life again because of the excellent information provided by wildside.

[wildside]

Hi all,

Even after extensive aerial spraying last year, the pines here in the Sierra de Grazalema are very much full of new nests this year.... Why? because the clever people in control decided to do the spraying when the caterpillars were still in egg stage with very few hatchling caterpillars at all to be seen.... If they had left it another month then maybe it might have been worth the destruction to other life forms from the organo - phosphates they used... EEK!

[johngrahamclark]

I would like to put a slightly different perspective on this problem. I planted about 1000 pines on my finca, partly to stabilise the land, they are now 15 years old and substantial trees. Given the problem with the caterpillars I should have made a different choice of trees, however we are where we are and I love my forestry, the paths, birds and animals they encourage.
This time of year (January) is the season for pruning fruit trees and cleaning up the land. It’s a time when you can safely light fires. As I work around the finca I collect the nests as soon as I see them and burn them with the rest of the farm rubbish. I have never had a problem with this and it is the only feasible and practical way to deal with the quantity of nests that I have. My forestry is completely clean I have no nests, my dogs are safe. The problem is that there are pine trees in gardens full of nests, often owned by absentee owners not here at this time of year. All the land is owned by somebody and the trees are their responsibility.
A practical tip, if you have pines don’t let them get too tall, cutting off a meter or two off the top will not spoil their appearance and it makes it easier to cut out nests.

[ajtg1952]

I only have one Scots pine and this year only 4 nests but much bigger than usual. The tree is over 30 feet tall. Fell off the ladders twice removing 3 nests and the one left is right at the top. I got that one down with my air rifle. Good fun as well as getting rid of the problem.

[AlisonM]

I read somewhere that firing bleach through a super soaker at the nests that are out of reach will kill the caterpillars, does anyone know if this is correct and if so the best time in their life cycle to do it? Also is there anything that can be sprinkled around the base of the trees to get them on their way down? Thanks