LDD moths (Lymantria dispar) are exotic pests that have been seen in great numbers on private and public trees in Pincourt.

You may have noticed hairy caterpillars on your trees or on your outdoor furniture lately. These pests feed on forest, woodland and urban trees. Their name derives from their ability to travel by attaching themselves to various objects.

If caterpillars are feeding on your trees, know that they can cause significant defoliation to trees on your private land as well as trees in urban woodlands and natural forests.

Here is what you need to know:

  • In large numbers, they can defoliate individual trees and large strips of forests.
  • If defoliation happens several years in a row, some trees can die.
  • Major infestations last two to three years and occur every seven to ten years.

Taking action now will reduce the severity of damage caused by LDD larvae.

  • Control Measures

    Once you’ve identified that LDD moths are feeding on your trees, it’s important to destroy as many as you can.

    Three recommended methods are manual control, trap use and biopesticide spraying.

    Manual control

    A simple and effective method that requires daily intervention. All you need to do is inspect your trees and, using gloves, scrape the caterpillars off the branches and tree trunks into a bucket of soapy water.


    Install Tanglefoot sticky traps around the trunk of infested trees. The caterpillars will get trapped in the sticky paste and die. Remove the traps when the caterpillar stage is over in July.

    Burlap (or other flexible material) can be used to create a trap in which the caterpillars will go hide when they are not feeding. These can be installed around tree trunks and large branches and will need to be inspected daily to manually destroy the caterpillars hiding under the burlap. Again, remove the traps once the caterpillars disappear.

    Using the biopesticide BTK

    Btk or bacillus thuringiensis kurstaki is a biopesticide that is specifically designed to kill caterpillars without being dangerous to birds and other insects.

    To be effective, it needs to be sprayed on the foliage of trees as it has to be consumed by the larvae. Make sure you follow the instructions for mixing on the bottle and spray on foliage in the evening or on cloudy days. Repeat at least two or three times every four to five days. Spray again if it rains.

    If caterpillars are congregating on tree trunks, patio furniture, exterior walls or foundations, a simple and efficient way to destroy them is to spray them with soapy water or insecticidal soap. 

  • Intervention Schedule
    Gypsy moth control measures
    Calendar Life Stage Control Options
    August to May Egg masses Remove egg masses and discard
    End of April- to end of May Early stage caterpillar

    - Apply BTK on the foliage of trees

    - Spray soapy water or insecticidal soap on larvae

    End of May to end of June Late stage caterpillar

    - Spray foliage with Btk on affected trees

    - Spray soapy water or insecticidal soap on larvae

    - Install sticky traps

    - Install burlap traps, check every day, and destroy larvae


    June-July Pupae Remove by hand and destroy
    July-August Moths Focus on other stages

    *With permission of www.ecolojardiniè and adapted from 

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