ARCHIVED - Murcia close to maximum alert status for pine processionary caterpillars

The warm weather is causing a plague of the caterpillars which are potentially lethal for dogs and cats

As alert dog and cat owners will doubtless be aware, the pine processionary caterpillar season is currently in full swing in the Region of Murcia, posing a lethal threat to pets as inquisitive animals which can be attracted by the bittersweet smell of the creatures and may try to eat them.

The results can be fatal; as few as three or four will kill a medium-sized dog, and just one may produce death in a cat as the bristles of the caterpillars become embedded in the tongue and cause necrosis. By the time the owner notices the problem, it is usually too late for veterinary treatment to do much except ease suffering.

In addition, small children are also at risk although to a lesser degree, with the irritating bristles capable of causing a severe rash.

In the past the appearance of the processionary caterpillars used to occur between late February and April, but as the climate becomes warmer they are dropping from their cocoons in pine trees earlier and earlier, and in and around the city of Murcia they have been seen in early January for at least the last three years. In residential areas with gardens they are especially troublesome, as although Town Halls and neighbours’ associations can spray trees in publicly owned land many people have pine trees in their gardens, and do not notice the problem until the caterpillars are already making their way nose-to-tail along the ground as they exhibit the behaviour which gave them their name.

According to those involved in combating the spread of these annoying caterpillars, which are part of the life cycle of a moth which thrives in pine trees, the start of 2020 has seen their numbers reach veritable plague levels, and nests are dropping even from trees which have been treated year after year, either by spraying or by the injection of insecticides into the sap. The problem has been exacerbated by the higher than usual temperatures of the last three weeks or so, and in Murcia it is reported that the alert level has been established at 4 on a scale of 0 to 5.

The conditions are now perfect for the caterpillars to fall to the ground, as they need a soil temperature of between 20 and 25 degrees to bury themselves in the ground to pupate, before emerging as unspectacular light brown moths which may live for only a day: enough time for them to mate and leave eggs near the top of pine trees for the following year.

Each female can lay up to 200 eggs which might be contained in a single nest, and therefore it is not uncommon for there to be at least 2,000 caterpillars waiting to drop to the ground in any given pine tree.

There are treatments, but of course they are expensive. The most efficient is to use chemicals which act on the larvae when they are feeding on the pine needles, while other alternatives involve the use of pheromones and traps, but most local authorities resort to cutting nests out of trees and disposing of them safely when they are reported. In the city of Murcia a pest control company has been contracted at a cost of over 1.1 million euros to combat the pine processionary, but this year it seems that in some areas they are fighting a losing battle.

As ever at this time of year, then, it is advisable to keep a lookout for the lines of processionaries on the ground when close to pine trees, not only in the countryside but also in built-up areas, and especially if you are a dog or cat owner. If you find them on the ground in the garden spray them before collecting them (using gardening gloves, a plastic bag and a trowel or small spade), tying the bag and depositing them in the rubbish.

Attempting to pick them up alive can cause the caterpillars to eject severely irritating bristles, and those tempted to throw a branch and a nest on a bonfire run the risk of the bristles flying out with the smoke from the fire.

Click here for further information about the pine processionary caterpillar, a major threat to cats, dogs and even horses in south-eastern Spain.

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