Alexander M. Patch Elementary School
Stuttgart, Germany

Caterpillars - Oak Processionary Moth

Last winter was a friendly season for insects. As a result this could produce a high number of caterpillars, such as the larvae of the Oak Processionary Moth (Thaumetopea processionae).  The caterpillars hedge in May and pupate in the second half of  June.  During the daytime they stay in a nest, typically on the lower side of an oak branch. 

On the skin of the caterpillars are many hair-like projections called setae.  When the larvae shed their skin, the setae can break off and float through the air. Contact with these hairs can cause skin and eye irritation.  This can occur immediately or up to 2 hours after exposure.  Exposed skin may look like mite or insect bites.  Physicians call this condition caterpillar dermatitis.  Caterpillar dermatitis may be uncomfortable but rarely creates an emergency.  Very infrequently such exposure can result in an allergic reaction which would require immediate attention.  If you experience effects other than those on the immediate area of exposure such as nausea, vomiting, chest tightness, wheezing, swelling of unexposed skin, or on the face, lightheadedness, or dizziness; then you should seek medical care immediately. 

Avoiding Caterpillar Dermatitis 

l Children should avoid playing next to infested oak trees during May through July. 

l On hot and dry days the setae can float longer in the air, so the risk of skin contact is higher. 

l Cover your skin when near oak trees.  Do not walk in the underwood of forests. 

l If you detect contact with the setae, then shower as soon as possible.  Be sure to wash your clothing.  Benadryl or Hydrocortisone skin cream can reduce the itching.  In case of severe exposure consult a health care provider.