The Caterpillar of the Pine Processionary Moth

The Caterpillar of the Pine Processionary Moth

In the area of Spain where I live there is a pesky little critter that is a real nuisance at this time of year it is the caterpillar of the Pine Processionary Moth.

In late August the female moth lays her eggs on the pine needles which will provide the food that the caterpillars will need when they hatch. The female can lay up to as many as three hundred eggs which at this stage are really minute and they are all clumped together when she deposits them in a mass on the pine needles on the pine tree.

It takes about a month for the minute caterpillars to hatch but once hatched they eat and grow quite rapidly. The caterpillar goes through five growth stages at the end of each stage it moults its skin to accommodate its new growth. It is not until the caterpillar reaches the stage of it third moult that it begins to build the communal silken nest that you see adorning the pine trees.

The pine tree is their food source and the nest protects them from the cold and wet of the winter months. You will often find more than one of these nests on a pine tree and seeing that there can be several hundred caterpillars in a single nest  they can do quite a lot of damage to the tree stripping bare the branches near their nest as they eat the pine needles voraciously.

A Caterpillar Nest in a Pine Tree

Dangerous Little Critters

The caterpillars forage and eat by night and sleep by day, this way they avoid attack from many of the daytime predators such as the birds and certain types of wasps.

The caterpillar of the Pine Processionary moth can be quite dangerous to both pets and people because they have fine hairs that are poisonous. These hairs are part of the defensive mechanism of these caterpillars and can be fatal to cats and dogs and in some very rare cases also to people if they are allergic to them.

You can see the hairs quite clearly in the next photograph.

A Close up of the Pine Processionary Caterpillar


We have a dog and on our normal dog walking route there are many Pine Trees that have these nests in them so at this time of year we go out and try to remove all of the winter nests of these caterpillars that we can find.

We have found in previous years that if we do this before the caterpillars begin to process then we can remove the nest and reduce the infestations on our dog walking route to almost zero. In addition to this we have found that each year we are finding less and less of these nests in the Pine trees near us.

Unfortunately at this time of year the nests of these caterpillars are decorating many of the local pine trees and each one of these nests can house up to several hundred of these caterpillars.

Below are photographs of some of these nests that I took this morning I have enabled the 'click on image to see full size' feature and if you have the time I think that you will enjoy the photos more if you take the time to do this. I uploaded the photos at full resolution so that you can see the fine details.

You can see on the outside of the nests that there are some full grown caterpillars already out of their nest.

A nest of the Pine Processionary Caterpillar

Pine Processionary Caterpillar nest
Pine Processionary Caterpillar nest
Pine Processionary Caterpillar nest
Pine Processionary Caterpillar nest
Pine Processionary Caterpillar nest
Pine Processionary Caterpillar nest

In Procession

They call these caterpillars Processionary because that is what they do at the end of their 5th and final growth stage as a caterpillar. These processions take pace, when they go searching for a suitable site to pupate in; when the caterpillars set off to search it is always in a procession and at the right time of year you can see many of these processions of caterpillars in a nose to tail train following a leader.

The caterpillars are searching for soft soil that they can burrow into in order to pupate ready for the next stage of their lifecycle. Once they find the site they will burrow in and there they will change into a pupae and they will remain buried underground until they emerge the next summer to live out the final part of their lifecycle as a Pine Processional moth.

These processions normally take place around the middle to late February until about the middle of April. During this time great care has to be taken with your dogs so that they don’t come into contact with the caterpillars.

During these months when the caterpillars are processing we never let our dog off his lead on his walks because as vigilant as we are at removing all the nests that we can see at some point we usually see some of these caterpillars in procession on one of our walks.

In Procession

Take Precautions

The caterpillars normally build their nests on the side of the tree that faces the sun. This makes the location of the nests a little simpler. Once we have located a nest we cut it off the tree and place it in a carrier bag. It is important when doing this to take precautions as the hairs of these caterpillars can cause some very nasty rashes and these can take some time to heal and can be very sore and itchy, you especially don’t want to inhale these hairs or have them get into your eyes. Rubber gloves are a must as you don’t want any of these hairs to come into contact with your skin.

Cutting the Nests from the Pine Trees

Making the Place safe for dogs

Information on the web suggests that if you have an infestation of these nests near you to contact the Guardia Civil, who will arrange for their removal, but the resources that they and the local Ajuntamenta have are extremely limited and often nothing is done.

Opinions differ as to whether you should remove the nests yourselves but we really can’t risk the health of our dog as he is a much loved family pet and to us irreplaceable. Because these caterpillars are so dangerous to dogs we therefore feel that we have to go out and remove as many of their nests so as to remove as much risk as we possibly can and we know we are not alone as other pet owners do the same for the same reasons.

Trying to make our part of the world a safer place

I hope you enjoyed the photographs of our attempts to make our part of the world a little safer for the dogs of our area.

Insect based Hubs

If you enjoyed this Hub you might like my other insect based Hubs.

  • The Life Cycle of the Dragonfly - In this hub I want to look at the life cycle of the Dragonfly and I suppose that the best place to start is at the very beginning. This is where it all begins;
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  • The Caterpillar of the Pine Processionary Moth - In the area of Spain where I live there is a pesky little critter that is a real nuisance at this time of year it is the caterpillar of the Pine Processionary Moth.

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Comments 47 comments

alekhouse profile image

alekhouse 7 years ago from Louisville, Kentucky

Very good hub..informative, well organized and well written. Thanks

Hello, hello, profile image

Hello, hello, 7 years ago from London, UK

Interesting read which I enjoyed. They are quite huge nest. Thank you very much and I glad to hear from you. I thought You deserted me. I loved reading your previous hubs. That is why I fanned you.

Ann Nonymous profile image

Ann Nonymous 7 years ago from Virginia

Very informative hub and great pictures and I am officially grossed out! LOL...So sorry you have to deal with these critters Maggs. The very hungry caterpillar, indeed!

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

alekhouse thanks for the encouraging words I really do appreciate them, and thanks for being so quick to view.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

hi Hello, I am so sorry if I am not around as much as usual this is because I have been without my computer since before Christmas (it died now it is just an expensive door stop) fortunately I am able to borrow one when it is not in use, but of course my access is now limited by this.

I am glad that you like my hubs and I really appreciate the fact that you fanned me and that you are kind enough to leave me comments, you don’t know how seeing your name in my hub comments lifts my day. As soon as funds allow I will get a new computer of my own, but it won't be just yet, there are other priorities that we need to attend to before this happens.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi Ann, yes they gross me out too, that is why I only take the little critters photos, looking through the lens seems to separate you from them some how. I am glad that you like the photos, I was quite pleased with the way they came out myself. Thanks so much for leaving a comment.

50 Caliber profile image

50 Caliber 7 years ago from Arizona

Maggs224, quite interesting as in the states I have seen these and incorrectly it seems they call them "bag worms" I suppose due to the appearance. I have seen groups of Pines in northern Arizona turn brown and die from these infestations. They are more aggressive and crews spray poisons on them with bucket trucks as some of the Pines reach very tall heights that require a bucket and a needle spray to target the bags up higher than the truck can reach like 75 feet in some instances. I'm not sure they are one and the same but by your vivid and quality photos they seem to be. I've never known of the poisonous nature of them and have had them on my clothing while hunting and just brushed them off. Now I'll have to do some deeper research to see what we have. Thanks for a great hub.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi, 50 Caliber, it is amazing how many things in our everyday environment go unnoticed until it actually affects us in someway. I doubt that I would have ever taken any notice of these nests and caterpillars if we didn’t have a dog.

Each year our dog has to have certain shots, and the Vet warned us about these caterpillars and the danger they represent to the dog and cat population and so did about every other dog owner that we met while out walking the dog when it was time for these critters to go walk about.

Of course once we were made aware we saw these things everywhere and of course my hubby being an ex military man (Navy) he couldn’t settle until he did something about it.

RNMSN profile image

RNMSN 7 years ago from Tucson, Az

ugh gross they were in bay minette too!!!

I wonder what the highter power had in mind whe he made these things>

sorta like gnats....what good are they...

I dont know the higher power says, lets put them out there and make them bother people riding bicycles...they will get gnats in their eyes and we can laugh laugh as the try and steer with one hand and get it out with one fairly clean finger with the other hand lololololololo?????????

geeZ maggie I miss you'

I love you

dont you guys in spain get an income tax refund???? not that mine did us any good this yr...9 bucks can you believe it??? but hey I broke payout today :)

that bicycle gets closer and closer eh?

50 Caliber profile image

50 Caliber 7 years ago from Arizona

maggs224, from time to time I take my dogs north and we run about in the woods and if not for this hub I would have never known about the possible harm. The next trip I plan to stop at a Vet in one of the towns and ask if these are the same as what you have and if they have seen those problems. Thanks!

ethel smith profile image

ethel smith 7 years ago from Kingston-Upon-Hull

As a dog lover I have to say good on ya. Thankfully most if not all British caterpillars are much safer.

Mystique1957 profile image

Mystique1957 7 years ago from Caracas-Venezuela


I love a good informative hub anytime! I learned something new today, which I am grateful for. Very well written and researched!

Two thumbs up(away from them critters!)

warm regards and blessings to you,


maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi there Barbara, one thing I am sure about is that God has a great sense of humour and watching the antics of his creation I am convinced gives Him plenty to laugh about without having to create things like poison critters and gnats, so I too just don’t understand the reason for some of the critters He has created either. Lol. You will have to send me a photo when you get that bike.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi there 50 Caliber, well like my old dad use to say, ‘forewarned is forearmed’ the good thing is that they are only a threat for part of the year the rest of the year you are safe from them.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi Ethel, We Brits do tend to be soppy when it comes to our animals, and we go way out of our way to make sure nothing bad happens to them don’t we. Britain seems to be blessed when it comes to dangerous animals and creepy crawlies we have relatively few that are harmful to either our pets or us. Still one consolation is that in Spain we at least have good weather most of the year.

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi Al, as always your comments really bless me you are very kind and encouraging, thank you for your warm regards and blessings, it is nice to receive them both and I send the same right back to you

Rik Ravado profile image

Rik Ravado 7 years ago from England

This sounded quite a boring topic but it is so well written and well illustrated that I got hooked - also a great resource for someone with the same problem - well done!

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi Rik I am so pleased that this hub managed to hold your attention, and thank you so much for taking the time to leave such an encouraging comment.

marieryan profile image

marieryan 7 years ago from Andalusia, Spain

This article caught my eye, Maggs, as we have these little 'critters' as you say, down here on la Costa del Sol!

Your photographs are fantastic!

maggs224 profile image

maggs224 7 years ago from Sunny Spain Author

Hi Marie I am glad that you liked the photographs I was quite pleased with the way they turned out too.

Michael Shane profile image

Michael Shane 6 years ago from Gadsden, Alabama

Very interesting & informative hub!

maggs224 profile image

maggs224 6 years ago from Sunny Spain Author

Hi Michael I am glad that you found it interesting, thanks for leaving a comment.

lxxy profile image

lxxy 6 years ago from Beneath, Between, Beyond

I've never heard of this caterpillar species before. Next time I'm walking in the forests of Spain and see these marvelous cocoons...or a procession of little fuzzy brown things, I'll be sure to keep my distance!

Thanks for sharing this with us, great pictures too!

maggs224 profile image

maggs224 6 years ago from Sunny Spain Author

Hi lxxy glad you liked the photographs, and as for keeping your distance, that's a very smart or should I say lxxy thing to do. Thanks for taking the time to leave a comment it is very much appreciated.

Lizzie. 6 years ago

Thankyou maggs, for a great write up and great photo's! I look after dogs here in Spain and i always look out for these horrid things when walking the dogs and try to make people aware of them also. In the 12 years i have lived here i have known of some bad incidents with these nests, one being so bad a poor dog lost half of his tongue from licking the nest, poor thing was left all day in a garden which was full of these things! Your information on these nests, explains it all so good i have put this link on my 'Pampered Pooches!' page on Facebook! Please feel free to look and press the 'LIKE' on the page if you do! Again thankyou!

maggs224 profile image

maggs224 6 years ago from Sunny Spain Author

Hi Lizzie, Thank you so much for your comments. I am so glad that you enjoyed reading the hub I would be really interested to see your 'Pampered Pooches!' page on Facebook! But I don’t know how to get there can you give me a link?

Lizzie 6 years ago

Hi maggs, this is the link:

maggs224 profile image

maggs224 6 years ago from Sunny Spain Author

Hi Lizzie thanks for the link and for the link :-D

brian thurlborn 6 years ago

yeh very interesting but the guardia here in spain are not interested (they are just looking for a easy life) so just cut the branch off and BURN IT!!!! like i have just done today!

maggs224 profile image

maggs224 6 years ago from Sunny Spain Author

Hi Brian, good for you! The more that are taken care of the better I like it :)

mailxpress profile image

mailxpress 5 years ago from New York

They look so innocent. Good read and I learned something new.

maggs224 profile image

maggs224 5 years ago from Sunny Spain Author

Thank you mailxpress for taking the time to pop over and read this hub and you are right they do look innocent but unfortunately that is not the case.

sandra walsh profile image

sandra walsh 5 years ago from Axarquia

Very interesting and informative. I live in the Axarquia area with a lot of wives tales going around. This has been the most accurate information about these critters I have yet to find. This is a year later than the article was written but we just moved here the past summer. We have already lost one dog to toad poisoning and we're not ready to lose are other 2 dogs to the processionary. Unfortunately the people who owned the house before us had planted many pine trees... lots of nests. At first it was okay to remove the nests because they were low but now we are dealing with nests in trees that are 7 meters high and haven't been able to remove them. They are on our property hovering over the fruit orchard. We stopped by the ayuntamiento and they say they have nothing for this year to help with the processionary removal. Very strange because I thought all communities were alotted funding to take care of this pest. Now we are forced to risk and climb tall trees to remove the nests.. I'm afraid to but must do it for fear of something worse happening in our garden. Don't know who to turn to so if anyone has a suggestion as to how I can get help or remove them safely please let me know... I'm going to do it anyway. Thanks Maggs. I have read and love all your writings.

maggs224 profile image

maggs224 5 years ago from Sunny Spain Author

Hi Sandra, we were fortunate that around us most of the trees were not as tall as yours are. I think that a lot of Ayuntamientos have gone broke and are having to make cut backs in every area and with the EEC in trouble also and new members being added to the community Spain is now no longer a high priority for funding.

I hope you manage to clear your property of these nests and I hope you can get some help with their removal.

The good news is when you do get your property free of these nests it is much easier to keep it free good luck with your fight.

sandra walsh profile image

sandra walsh 5 years ago from Axarquia

Hi Maggie, we have been blessed with good neighbors who I have just come to know in the last week or so. Through them I've gotten my prayers answered. I've got people helping me with re-landscaping the property directly around the house and another chap who is a professional tree surgeon and has a lot of experience with the nest. He's asking for a rediculously low compensation even after seeing and aknowledging that we had a difficult situation. But the new friend I made who sent him there assured me that all was legit and that they are only glad they could do something for us. I just can't believe it! There were so many problems I was ready to give up and suddenly everything is just turning around. I'm grateful that I've met such wonderful people.

maggs224 profile image

maggs224 5 years ago from Sunny Spain Author

Wow Sandra I am so pleased that things have turned around for you so quickly you are blessed to be surrounded by such great neighbours.

Just a little bit that has nothing to do with this subject or your comments but my daughter married a Walsh her name is now Sarah Walsh lol... so your name grabbed my attention right away. Well I did warn you that this bit had nothing to do with anything.

Thanks for letting me know how things have turned out I couldn't be happier for you.

sandra walsh profile image

sandra walsh 5 years ago from Axarquia

Your daughter, did she marry an Irishman, welshman or a Canadian. The Walsh side of my family had immigrated to Ireland and then to Canada. My father's family is Canadian. Im the first of family born in the USA. It's interesting because my great uncle has written a small book on our family's history. I hope to receive the story sometime soon. I've been told, not sure, that we still have some family in Cork and in Dublin and that some of our family still has contact with them... perhaps I should dig deeper into this. Although, I must admit that Walshes do get around in this world.

Gem 4 years ago

Hi, very informative article. Our cat found some and managed to poison herself, luckily I found her and rushed her to the emergency vet within ten minutes - my vet said her throat had closed and she was turning blue!! She is fine now, though sulking as she and our dogs can no longer go out in the garden at this time. We have lots of huge pine trees which have now been fumigated by a professional as they were covered in nests, apparently you can hang moth traps in the trees in the summer too - thus diminishing their numbers.

maggs224 profile image

maggs224 4 years ago from Sunny Spain Author

Hi Gem, I love hubpages it seems I learn something new every day, I had not heard of putting moth traps out before I read your comment it makes sense. I am so glad that you got your cat to the vets in time it is lucky that you knew what had happened and very lucky that you found her in time. Thank you so much for taking the time to leave a comment :D

alan 2 years ago

hi can you cut the nest out and burn it or what do you do

maggs224 profile image

maggs224 2 years ago from Sunny Spain Author

Hi Alan, try my friend Izzy's hub it goes into detail I think that it will answer all your questions

al 2 years ago

Hi there, recently moved to Spain, near madrid. Have my two dogs here, and have heard the horror stories about these caterpillars. Can anyone tell me what to do, first aid wise, if you think your dog has been close. And any idea exactly when these bigger hatch and decide to invade my garden. I see 2 big nests here. Help please, totally paranoid now. If anything happened to my dogs I'd have a meltdown.

Sandra Walsh 2 years ago

Hello Al. Yes, they have recently invaded the Madrid country side too. I used to live there. If they are in the yard or near by, cut the nests out preferrably midday and burn them as Maggs does. I do advise that if you have too many nests, that you get someone with experience to cut them out and burn them. If something happens to your pets, usually dogs and not cats, then you should immediately take the pet to the vet. Have a telephone number handy explaining to the vet that you need to know that he/she is on call in case of emergency. Oh, and ask if the vet has ever handled a situation of processionary with dogs. Most vets don't know what to do unless they were trained or had the experience before. This is a very important point. Eventhough there is talk of antihistamine as an antecdote I certainly wouldn't count on it because as of yet, there is no medicine that will take the toxin out or help the dog that has gotten the tiny needles in the membrane of the mouth or nose. It's not the needles that kill the pet but the swelling that does. This requires that a vet who will do a special scraping/scrubbing in the mouth to take the needles out carefully and inject something(they won't tell me). The most important thing in keeping your pets safe is to keep them on a leash at all times when walking ANYWHERE. Keep looking a few meters ahead of where you're walking. You will know it when you come across a processionary line... do NOT try and cross it. Do not let dog sniff it. Let it pass even if you have to wait a long time! You don't want to go over it with the wheels of your car either because you can track it back to your home where dogs pick it up on feet lick themselves clean and accidentally get needles in their tongue. If you cannot avoid going over it with the car on a track, then I suggest washing tires after crossing. I wash with a soapy water made with Ariel or another detergent that breaks down certain proteins and maybe might break down the properties in the needles of these caterpillars-maybe. BUT there is NO guarantee this works either. It is my own theory and remedy which I have not proven yet that it works. I just do it and it makes me feel better... less worried. AGain, as Maggs says, try her friend Izzy's hub. A very in depth story on these creatures. Hope this helps. I will try to post one of my pics of a processionary line.

sandra walsh profile image

sandra walsh 2 years ago from Axarquia

I forgot to add that we had gotten help from a former vet who gave us a cortisol/antihistamine to inject. There is very little time for one to get to the vet therefore it is recommended that you talk to your vet to keep something like this on hand... just in case.

maggs224 profile image

maggs224 2 years ago from Sunny Spain Author

Hi Al , the comment directly below your by Sandra Walsh contains some excellent advice, the time that you have to be most vigilant is around the middle to late February until about the middle of April when they come down out of their nests and you start seeing their processions.

As for first aid advice see Sandra's second comment she has been given a cortisol/antihistamine to inject by a former vet, you could have a word with your vet to see if he could give you something similar.

If you don't feel confident enough to tackle the nests yourself, then try your local Ayuntamiento's office (the local council office) they will be able to help, they some time deal with these nest free of charge, but if not they will be able to put you in touch with some one who will be able to do it for you.

Also read my friend Izzy's hub dealing with this problem I hope that this helps.

maggs224 profile image

maggs224 2 years ago from Sunny Spain Author

Hi Sandra thank you so much for your wonderful comment. The information and help you have given in your comment is certainly a valuable addition to the content on this page, and will certainly be of great assistance to people who come to this page looking for answers.

Thank you so much for taking the time to make such an interesting and useful contribution to this page, I am very grateful for your input. Maggs

Al 2 years ago

Thanks so much. I have my eye on them. I will also contact my vet about injections. Thank you.

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