Oak processionary moth: when is the season over?

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Duration of the season of the oak processionary moth

table of contents

  • What are oak processionary moths?
  • Period and allergy
  • frequently asked Questions

"Attention, oak processionary moth". You see this sign more often when you go for a walk. But why be wary of oak processionary moths and, more importantly, when is their season over? We'll tell you what you need to know about animals.

In a nutshell

  • Oak processionary moths are moths
  • Caterpillars cause allergic reactions
  • High season: May - September
  • Basically year-round allergy risk

What are oak processionary moths?

The oak processionary moth (Thaumetopoea processionea) is a Mothflying from July to September. It prefers warm and dry climates and is spreading increasingly throughout Germany as a result of climate change. The animals mainly attack all types of oak, preferably single trees, stand edges and light oak forests. In autumn the female lays up to 200 eggs, after which the animals die. The season does not end with the death of the adult animals, however, remaining caterpillar hairs pose a threat all year round.

Nest with oak processionary spiders
The nests of oak processionary caterpillars are found on oaks.

Note: If you discover nests of the oak processionary moth, you should inform the responsible health, horticultural or forestry department immediately. A notification requirement does not yet apply.

Period and allergy

The caterpillars of the oak processionary moth develop as early as autumn and then hibernate in their eggs until they hatch from April to May. After hatching, the animals join together in processions and wander into the treetop to eat. Every stage of development of the larvae increases the health risk for humans. From the third larval stage, around May, the caterpillars develop barbed stinging hairs that contain the nettle venom thaumetopein. The number of stinging hairs increases with each moult. The almost invisible hair breaks off easily and then penetrates the epidermis and mucous membranes. They are dangerous to humans and can cause the following allergic reactions:

  • Skin and mucus irritation
  • itching
  • Irritation of the mouth and nose with risk of asthma
  • dizziness
  • fever
  • fatigue
  • Conjunctivitis
  • rare: allergic shock

There is an acute danger especially during the caterpillar feeding season and in direct contact with the caterpillar. The caterpillars pupate from mid-June and become moths that swarm until September. But even in autumn and winter there is a persistent danger because the wind spreads the remaining caterpillar hairs. Empty moulting nests and remaining pupation webs are also preserved for years and represent a potential source of allergies. The season is never completely over, but the danger is significantly reduced in autumn and winter.

Oak processionary moth caterpillars
The caterpillars of the oak processionary moth gather in groups.

Note: Stinging hairs often stick to clothing and shoes. In order to prevent further toxic reactions, it is strongly recommended to wear clothing after contact with the animals and to change shoes and wash them at at least 60 degrees and also to clean other items thoroughly clean.

frequently asked Questions

How long does an allergic reaction last?

If left untreated, an allergic reaction triggered by oak processionary moth needs about 2 weeks to subside, but depending on the species, it can also be treated with various drugs.

Can the oak processionary moth be dangerous for my pet too?

Yes, most animals are protected by their fur, but uncovered areas such as the snout or mucous membranes can react. Dogs are particularly often affected. If necessary, rinse the affected areas as quickly as possible with clear water and cool, if in doubt, consult the veterinarian.

Can I still eat fruit from my garden if a tree nearby is infested?

If the fruits are not in the immediate vicinity of the infested tree, they can be eaten. As a precaution, however, the harvest should be harvested with gloves and washed thoroughly.

Can I remove the nests myself?

No, the removal of the nests should be left to experts, as they have the expertise and appropriate equipment.

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