Processionary Caterpillars or Pine Caterpillar


As every Spanish child knows, don't even think about handling the hairy caterpillars of the pine processionary moth ( procesionarias in Spanish).

If they are touched, their hairs release an extremely nasty allergic skin reaction. Children have been known to go temporarily blind from rubbing their eyes after picking them up. They live in easily identifiable silvery nests in pine trees throughout Mediterranean Spain.

Forewarned is forearmed and this bug is one definitely worth writing about as it can cause much harm! More commonly referred to as the pine processionary caterpillar as its name implies, the pine processionary caterpillar is a kind of caterpillar that lives on the tree tops of Pine Trees. The word processionary comes from the fact that they line-up forming long caterpillar lines that can reach several meters long, although generally they only measure around a centimetre in length. They live in the forests of Spain, Italy, France, Northern Africa and other Mediterranean States.

If you had a walk in the woods and your skin itches or has irritations or feels that a couple of insects have bitten you or ....your eyes irritate ...or if your dogs mouth has started swelling or dribbling / foaming (may even lead to vomiting) or... if you see a long line of caterpillars on the road (hopefully very flat ones), floor or tree trunks, then yes -you have been unlucky enough to have met one of the Mediterranean's worst pests!

These pine caterpillars live mostly in Pine trees. Trees “infected” with these worms tend to have white coned like nests. These become especially visible in the latter months of winter. The trees with these white nests normally do not have such a healthy aspect, and if carefully observed one will notice that the branches close to the nest have started drying out. This is because the worms feed on the tree. Weak trees, small trees or trees with many nests may die thanks to these nasty creatures as each nest contains up to 200 caterpillars. The nests themselves are perfectly built, normally facing the sunnier side of the tree and although their tenants like warmth, they can unfortunately withstand in their nests temperatures down to -12 Celsius.

The biological cycle of these Pine Processionaries starts in summer when moths start popping up from the ground. These moths have been buried for most of the summer while they were in their cocoon stage. Incredible though it may seem, these creatures can be buried up to several years until they sense the best condition to resurrect. The moths dig themselves up during the night, find a male or female moth, mate and fly towards the most appetizing Pine tree in the area, lay their eggs and die. Around four weeks later, the eggs start hatching. A couple of weeks later the bugs start getting nasty as they acquire an outer layer of thin hairy needles. These needles will serve as their defence mechanism and anytime they find themselves in danger, they will expel these needles causing the previously mentioned irritation on their prey. The itching and irritation effect is caused by histamine on the needle tips (only visible on the caterpillar meaning if you see it, you are too close for comfort). The caterpillar themselves leave the nests at night, when they are less vulnerable to pray such as birds. They feed on different parts of the tree and make there way back to the nest before morning. These insects rarely leave their host tree until they are ready to find an adequate place for cocooning. This occurs normally in March – mid April.

How to fight the Pine Processionary
Getting rid of the Pine Processionaries is a difficult task. Governments in the Mediterranean region have spent millions in fighting these bugs and the results have not been as satisfactory as expected. The best time to fight them is when they are less vulnerable, i.e. when the first nests appear (end of summer). Nevertheless, the nests are also less visible during this time. Try to cut the nest down wearing gloves and not letting the nest come into contact with your skin (by the branch) and inject gasoline into it. That should kill anything inside. If you have chosen the most sensible option of pulling the branch down carefully dispose of it in a plastic bag or when possible – burn them. Unfortunately these worms like heights, and most of the nests will be found close to tree tops. If you can manage to explain yourself and wait until they can get to you, many town-halls will also help you deal with the problem free of charge - so give them a call before hand explaining the problem, their Spanish name is Processionaria.

If you are bitten
Once bitten you will probably get a rash. There is not much you can do now, but according to the locals I have spoken with, there are a couple of steps that can help you. First thing to be done is to wash the area with warm water – if possible shower as you may have been “hit” in other areas. Change clothes as soon as possible as the insects “hairs” may still be there. Be aware that rashes will probably occur in areas with higher exposure such as the face and areas susceptible to movement such as neck and upper area part of arm and elbow. All Pharmacies also sell pills and cream that will drastically reduce itching. If you believe you have been hit in the eye go to your doctor. Finally, the level of reaction depends much on the individual.

Your Pet - take care!

In this case, your pet probably means your dog as Cats tend to be a bit more clever and cautious with these things. Unfortunately, the dog does not even need to have seen one of these pine worms. Dogs have a bad habit of licking the area where the pet caterpillars have passed - having similar consequences as if the dog had been chewing on them. As mentioned above, symptoms that your dog has been in close contact with these creatures are dribbling or foaming from the mouth, and or several rashes close to the mouth and tongue. For dogs these creatures can be especially nasty as they can cause them to lose their tongue. This from what I understand comes from the intense itching and the dog simply scratches his tongue out or that the tongue simply dies. It is therefore recommended to act with total caution and call a veterinarian as they will know what to do. Be careful when the caterpillars are on the move, some people try to limit taking their pets into areas where there is a known problem at certain times of the year.

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