Health precautions and tips

Be careful – processionary caterpillars can harm you!

Processionary caterpillars (and possibly other hairy caterpillars) are urticarial, meaning that they cause variable levels of allergic reaction in people who are exposed to nest material or the hairs (setae) of the caterpillar.

Figure 1. Itchy rash on the neck from exposure to processionary caterpillar setae.

Contact with skin can cause wheals and widespread rashes (Figs 1 & 2) that may be accompanied by burning sensation, pain, itching and swelling. These symptoms may resolve quickly or may persist for days. Inhalation of hairs or exposure of the upper respiratory tract may result in difficulty breathing. If nest material or hairs penetrate the eye, they may result in conjunctivitis and injury to the eye. Individuals that are prone to allergy or asthma may be at increased risk of more severe allergic signs in response to caterpillar exposure. In some individuals exposure to caterpillars or to nest material may require medical therapy.

Figure 2. Foot following exposure to a processionary caterpillar nest.

If you are going to handle caterpillar material, take precautions and develop some safety protocols.

  • Caterpillar nest material and setae may be dispersed easily by wind.
  • Avoid skin contact with any material and in particular do not allow material to contact your eyes or mouth/nose.
  • Wear protective clothing including overalls or long sleeved outer garments, face protection and gloves.
  • Do not work with caterpillar material when it is very windy.
  • Be especially careful (or void altogether) working with caterpillars if you are prone to allergies or respiratory conditions such as asthma.

It is strongly suggested that protocols be developed prior to handling any caterpillars or nest material. Protocols should include how to manage inadvertent human exposure if individuals do develop clinical signs such as skin reactions, respiratory conditions or eye conditions. For more tips on caterpillar management, click here.