Invasive Gypsy Moth & Caterpillars at Wateridge Village

Thank you to the Manor Park Community Association for sharing the information included in this post.

The invasive gypsy moth and its caterpillar stages are impacting our trees! But it’s not too late to take action. Here are some concrete steps we can take RIGHT NOW to help our trees and wildlife and hopefully reduce the number of caterpillars and moths next year.

Please consider adopting a few trees in the neighbourhood as well as looking after your own! Here are some suggested instructions:

  1. Wrap trees in burlap, breathable fabric, or a combination of sticky tape with shiny tape top and bottom. If you need burlap we may be able to source it from Bridgehead, as they have been donating some to Manor Park – send us an email and we’ll let you know if we are able to get some! At the end of the infestation remember to wash the sticky tape off the trees! The caterpillars will crawl under the burlap at night so make sure to check in the morning.
  2. Mark the burlap, tape, or tree with your initials or name so that others know you are returning regularly to remove the caterpillars. Monitor the tree once or twice daily.
  3. Prepare a pail of water with some dishwashing detergent― the detergent helps dissolve the wax that keeps the breathing holes on the caterpillar’s side from closing; water enters the caterpillar and it drowns. 
  4. Remove the caterpillars by hand (wear gloves and long sleeves and pants, the hairs of the caterpillars carry a histamine that can provoke an allergic reaction smiliar to poison ivy) and drop them into the soapy water.

At this stage, the caterpillars are probably descending from the leaves at night and resting on the ground or at the base of the tree so checking your tree from 5 pm until dark and even after dark with a flashlight will net you a good haul of 2-3 inch caterpillars.  Then check the tree again in the morning when it starts to warm up:  7:30-9 am is a good time.  And, if you can, checking during the daytime also helps because the caterpillars will move around. 

Further Information

This moth has 5 stages of caterpillar growth (instars) if a male and 6 if female (she eats more to lay down fat to produce her 300+ eggs later this year).

We are about half- to three-quarters of the way through the caterpillars’ eating phases and as one caterpillar eats up to one square metre of leaf surface between hatching and pupating, it is important to continue monitoring our trees. 

The caterpillars will start to pupate any time now from late June or early July; this is a good time to look for the brown hard-cased pupae and flick them into a pail of detergent and water along with any remaining live caterpillars. Check any surface: walls, tires, car wheel wells, eaves, undersurface of branches and especially the trunks of trees.

Tips For Saving Trees

In the meantime, all is not lost for the defoliated trees. WATER YOUR TREES frequently but DO NOT add fertilizer to the water or sprinkle fertilizer around the tree. Leaf loss is a stress and combined with this spring drought, the impact is doubled. Fertilizer promotes new woody growth but you want leaves only. The tree has to ‘make a decision’ whether or not to use its starch reserves on new leaves and water helps promote re-leaf. The 2021 new leaves will be smaller and from the tree’s perspective, that is good. However, conifers, especially pines and spruces, may not survive because their reserves are in the needles which have now been eaten and they cannot replace the needles this year.

If it rains a bit more, a naturally-occurring fungus that multiplies in cool, wet weather will start attacking the caterpillars. A naturally-occurring virus may also show up.

Caterpillars hanging limply on the tree trunk head down or in a V-shape are being attacked by these diseases. This is normal and is to be celebrated by not removing the infected ones; nature’s biological control is in progress.

The adults will emerge from the pupal cases in August, mate (the adults fly in search of females, the females normally do not fly) and the female lays the eggs in a yellow soft and furry mass.  At that point, we should begin the egg scraping and destruction process all over again. 

Together, we can lessen the impact – so please keep up your good work and encourage others to join in!

We will be sharing an update on the next stage of capturing and destroying the moths in the coming days so stay tuned!