Don't follow the caterpillars in Spain

Don’t follow the caterpillars in Spain

Humans in general do not have a very happy relationship with creepy-crawlies. Most of us have a default assumption that creepy-crawlies are “nasty”, in the sense of probably in some way damaging to plants, fabrics, our structures, or our skin or worse.

There is something else as well. We can more or less anthropomorphise (and therefore think we understand) other forms of animal life, even dangerous predators (for example, sharks as psychopathic stalkers), but insects seem profoundly alien, especially those that do indeed do us harm.

Very near the top of the European list of nasty creepy-crawlies must stand the Processionary  caterpillars of the Pine Moth. These unpleasant creatures (there I go) are a major pest in many countries, including Spain, feeding on and eventually, if present in sufficient numbers, destroying host pine trees.

Their presence is conspicuous. During the winter months, the creatures build innumerable nests of a white silky material, which are suspended from the branches of pine trees. In shape they are like the upside down canopy of a hot air balloon, and they are a good few inches long from top to bottom.

Into these nests cram the caterpillars. They come out, through the walls of the nests, each night to munch on the trees.

As Spring approaches, the caterpillars prepare for the next stage of their existence. They get bigger; there is no longer room for all of them in the nest. Several will cling precariously to the outside, whilst the whole pullulates with the increasing overcrowding.

Then they migrate down to the ground. There, nose to tail in a caterpillar conga line, they slowly wriggle as one to find soft earth, in order to bury themselves and wait to become moths.

The moths live only for a day – mating and laying eggs are a very fast speed date and consummation. Basically the moth stage is a tiny but crucial instrumental feature of what is in effect the existence of caterpillars.

Other than creeping and crawling in procession, and destroying pine trees, what constitutes the caterpillars’ nastiness? It is that, as they mature in their nests, they grow virulent hairs. By the time they are ready to leave the nests, their hairs possess a poison that is extremely painful to humans, often causing severe allergic reactions.

 To animals the poison can be fatal. Dog owners keep their pets away from the paths where the caterpillars are likely to process. Any sniff, or other interference, can lead to an unfortunate chain of sting, wound licking, poisoned tongue and even death.

When walking in Spain in the early months of the year, beware the nests and the lines on the paths. Especially beware overcrowded nests hanging a foot or two above the path one is taking, where the creatures clinging on the outside look likely to fall on one’s head.

Make a detour.

I came across the UK Forestry Commission website. It seems that Processionary Oak moths/caterpillars have already reached west London, and that relevant local authorities have set up task forces to deal with them. The Oak creatures differ from the Pine ones only in their preferred tree and the seasons of their life cycle. Otherwise it is, with them, also nests , tree destruction and poison.

The FC advice contained one alarming piece of information that was news to me. It stresses the fact that the poisonous hairs easily break off the caterpillars and are easily blown on the wind. Even if you avoid touching the nests and the creatures, and dodge any falling on your path, the hair on the breeze may get you still. The hairs remain virulent long after separation from the caterpillars.

This knowledge could, like golf, spoil a good walk.

March 2016