Your want to know about swarming? Last year in late May and for the first half of June, we had the insects of Hell in our world. These are the European Gypsy Moths, brought here more than 150 years ago and accidentally released, from which point they have created a horror of our world of hardwood trees. They don’t do this every year. In fact, they are quiet and just annoying for anywhere from 25 to 30 years at a time, but for a couple of years, they swarm. Eat every leaf on every hardwood tree and then die.

It is the rapidly growing caterpillar of the Gypsy Moth. They invaded our oak woods last year, beginning as tiny, but growing enormous and ugly and hairy. And they are allergic, so if they brush your skin, there will be a lot of itching going on.


These voracious eaters can and will munch their way through the hardwood trees in the woods. I swear I can hear them crunching away at night. They eat night and day until they turn into moths. At which point they stop eating and eventually lay eggs and die.

I tried to knock all the caterpillars off  the door so as not to bring a dozen or more gypsy moths crawlies into the house with me. This one refused to be knocked off and clung to the door jamb with all several hundred of his sticky little feet.

The birds apparently don’t like the way they taste. There are so very many of them! At least they are (mostly) leaving my fuchsia in peace.


Gypsy moth is an insect native to Europe and Asia that has been severely weakening trees across North America. Gypsy moth was introduced to North America in the late 1860’s near Boston and has spread over the past century. Despite the successful use of insect predators, as well as fungal and viral controls, gypsy moth populations do occasionally reach outbreak levels and continue to expand their range.

Gypsy moth caterpillars defoliate host trees, mostly hardwood species, such as: oak, birch, poplar, willow, maple and others. During outbreak years, nearly all broadleaf trees may be completely defoliated, caterpillars appear everywhere, and “frass” (caterpillar droppings) appear to rain from the trees. Adult gypsy moths are only seen in mid-summer when temperatures are above freezing. This species is known to infest trees in woodland or suburban areas.


Gypsy moths can be found throughout southern Canada, across the eastern and central United States, and most of the western states. Populations have been found in southern Ontario, New Brunswick, Nova Scotia and British Columbia. Each population varies annually and fluctuates with local conditions.

Impacts of Gypsy Moth

  • Defoliates and kills large amounts of trees, affecting the many benefits provided by trees.

  • Economic impacts affect all forest users.

  • Caterpillars may chew small holes in leaves or completely strip a canopy, depending on age and population levels.


  1. Those beasties look (and behave) almost identical to one we have down under – the Cape Lilac (Tree) Moth. I appreciate the size of the problem makes eradication more problematic (i only have one lilac tree but at worst i estimate we had over a 1000 caterpillars and you definitely can hear them munching – or the debris dropping as they do).

    Here’s some local advice you may wish to try and if your friends join in you may have some effect?

    “Tie a piece of hessian or other thick soft material around the trunk of the tree. As the caterpillars crawl down the tree they will gather among the cloth to hide from the heat and light of the day. Simply gather up the cloth after sunrise and shake it over a tub of soapy water, maybe stirring it to ensure the caterpillars sink. Repeat the process for a few mornings and numbers will be rapidly reduced. Keep an eye on the tree’s pest numbers from time to time by shining a torch into the canopy to see if there are problematic amounts present.”



    • We do that, but we’re advised to use gaffer’s tape (big heavy slick tape) and some kind of oil that doesn’t hurt the tree, but keeps the bugs from crawling up. The problem is, they get to the top of the oak trees and drop DOWN on the trees then much till the trees are completely defoliated. This is way every country on earth is SO careful about letting people bring in wild plants. This is exactly what they are worried about.

      We have maybe a few THOUSAND oak trees? Big ones. These aren’t little trees in the garden. It’s a forest. If it were a garden pest, it would be a lot easier to manage, but it’s massive.

      And this is an old one. Been making a mess of a forests since 1865. The lack of rain makes it much worse.


      • Yeah – i got that your problem was related to the size of the forest, not garden.

        The gaffa tape is more of an obstruction, the hessian/wrinkly cloth is a trap you then need to empty and kill the beasties to reduce numbers. This will only work, if like our moth, yours ‘hide’ from sunlight somewhere on the ground and return to the canopy at night. Ours appear to eat from the top down but they go for the young shoots first as they are the tastiest then work down to the older shoots each day as the new shoots disappear. You can watch/catch/smash the caterpillars as they climb the trunks at sunset here. Another trick is to give the bugs somewhere to hide, like under a plank or flattened cardboard box near the tree base then lift it and pour boiling water over them before they begin their march up – but like i said, it only works if your bugs actually come down in the day.

        Because of our unique wildlife and freedom from rabies Aus has probably THE most restrictive quarantine regime of any country – even so we have several eco disasters from imported pests, including a couple introduced on purpose by the government!

        I guess this wasn’t seen as such a big issue at the end of the (Un)Civil War huh? 😉



        • These guys get to the top of the tree and they eat continuously until there isn’t a twig or leaf left on a might oak that a couple of hundred feet high. They don’t hide from anything. They eat. Eventually, they eat themselves out of existence, which is why two years is the usual swarm. At the end of two years, they will usually disappear for another 20 to 30 years. I just have to live through it.


          • I’m sure it can be a downer, but from one who does not have to suffer it, i guess if you’ve had ’em for 150 years and you still have 200 ft high oaks then the damage they do is more cosmetic than environmental – no? Would be much worse if you had no new trees to replace the ones that die! I try to be grateful for any mercies 🙂



  2. We have one or two, not legions of wriggling nastiness. As for the neighbors, I see you’ve been looking at properties here in my neck of the woods! How else would you know about the local loonies? Welcome, neighbor! 🙂


  3. What a great idea for a 1950’s science fiction classic. Invasion of the Gypsy Moths. Starring Hugh Marlowe and Gloria Talbot! Bring me some popcorn, please!


  4. The creepy-crawlies? Again? Here, let me interest you in a few properties where the Monster from Green Hell is not your next door neighbor…


    • Well, it’ll be one more year of decimated trees then, with a little bit of luck, they’ll become mere nuisances again for another 25 to 30 years. I went through this with the tree guys and there’s nothing more we can do. If there was anything, we would do it.


    • They aren’t back. Yet. Not until late May and early June. But the eggs are around and we all know, they’ll be back. MAYBE not as bad as they were, but they will return. Hopefully, though, just this one year and then gone for another 25 or 30. At least they don’t do this every year.


    • Yeah, very Stephen Kind. Except we know they will be back. How bad they will be, we don’t know for sure. It may not be as bad as last year and it should be the last year because they seem to go to sleep for 20 or 30 years between swarms. We will do the best we can. It’s just going to be hard going.


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