|Originalartikel:||Burri, M., Schniepper, M. (2006): Schmetterlingsraupen mit Brennhaaren. Merkblatt zu Arbeitssicherheit und Gesundheitsschutz in den Strassenunterhaltsdiensten. Herausgegeben von der Koordinationsgruppe Arbeitssicherheit im Strassenunterhalt (KGr AS SUD). www.nationalstrassen.ch|
|Autor(en):||Monika Burri, Maja Schniepper (Gruner AG)|
Some species of caterpillars have urticating hairs which can cause extreme itching, skin irritations and damage to eyes and the respiratory system. Therefore care must be taken during work being carried out along the edge of forests, on embankments or whilst tending trees.
Fig. 1 - Oak processionary moth caterpillars.
Photo: Entomology (WSL)
Fig. 2 - Pine processionary moth caterpillars.
Photo: Entomologie (WSL)
Occasionally during the course of maintenance work being carried out along the edge of forests or on street embankments health problems caused by three species of moths can occur. Contact with the stinging hairs of these caterpillars can lead to skin irritation and/or allergic reactions of the skin, mucus membranes or respiratory systems. The species in question are the following:
Most of us regard butterflies as colourful messengers of summer. Some people are aware that caterpillars can eat voraciously. For instance, the cabbage white dines in the vegetable garden. The mottled umber can damage fruit plantations by eating buds, leaves and blossom. The orchard ermine wraps up the left over bare wood and its surrounding area in white webs. Asian gypsy moth caterpillars manage to defoliate whole forests during their rare mass outbreaks and are a nuisance to people living near by when they move into gardens and houses by the hundreds or even thousands.
All of these species catch our eyes with their webs, nests and intense defoliation, but although they cause a certain amount of damage to cultivated plants they are however harmless from a health point of view.
The three aforementioned species are also noticeable thanks to their nests, webs, defoliation and caterpillar processions but they can also cause health problems. These caterpillars have stinging hairs which can cause itching, skin irritation and also eye problems or damage to the respiratory system.
Fig. 3 - Infestation of pine processionary moth caterpillars.
Photo: Entomology (WSL)
Fig. 4 - Gold tail moth caterpillar.
Photo: Beat Fecker (WSL)
Urticating hairs protect the caterpillars and their later stages of development (Pupae, moth, egg) from predators.
The urticating hairs of the golden tail moth, although less aggressive, are however used for protection in every stage of development: the hairs which are produced only by the caterpillars are woven into the pupae cocoons the female then strokes them onto her abdomen from where they make their way into the egg clutches during egg laying.
Skin irritations (caterpillar dermatitis)
One reaction after contact with stinging hairs of the gold tail moth may be extreme itching; this can occur hours after contact, but may continue over several days. Although only a slight rash occurs after contact with the gold tail caterpillar extreme itching can prevent a person sleeping. After contact with the stinging hairs of oak processionary or pine processionary moths the following symptoms may also occur:
In the case of processionary moths a further complication is that increased caterpillar contact increases the sensitivity and therefore the intensity of reaction of the affected person.
|Fig. 5 - Possible results of contact with the stinging hairs of processionary moths.|
Immediate measures to be taken when affected
In Switzerland health problems caused by caterpillars are treated by health insurance companies as accidents (analogue with tick bites).
a) Assessment of the situation
After a situation has been assessed and it is clear that there is an infestation of caterpillars with urticating hairs then a plan of action will be prepared using the following guide lines:
b) Prevention measures
In areas infested by gold tail or pine processionary moths the total removal of all possible winter nests can provide infestation free areas which should last at least up until the following autumn.
Fig. 6 - Small eggar.
Photo: Beat Wermelinger (WSL)
Fig. 7 - Ermine moth.
Photo: Beat Wermelinger (WSL)
Harmless species which have a similar biology and whose population could be endangered should not be controlled:
a) Small eggar
Wide spread in the canton of Wallis, otherwise sporadic in the cantons of Tessin, Bündner Rhine Valley, the area around Zürich, and in the Walensee area. Due to its rarity it should be protected. Nests should never be removed!
b) Ermine moths
Nine very similar species, generally very widespread.
The three species with urticating hairs were at one time more widely spread in Switzerland and more common. Their population was drastically reduced by the thoughtless use of insecticides in agriculture. In Switzerland and in near by neighbouring countries they are now once again on the increase. This increase is being encouraged by global warming. Distribution maps can be found in the leaflets (see download).
The pine processionary moth has been observed for some time in several areas in southern Switzerland. Since the beginning of the 1990’s there has been an increase in the appearance of the oak processionary moth and the dark gold tail moth: with the oak processionary moth occurring more rarely than the dark gold tail moth. All three species are capable of mass reproduction.