Saturday, August 21, 2010

Little Green Worms

At least that's what they look like to me
Wouldn't you agree?

My poor baby birches are being attacked by these small green monsters.  The stress of being newly planted and perhaps not watered quite enough (okay, I admit, I don't water as often as I should) has made them susceptible to this.
Is that black stuff caterpillar droppings?
Luckily I discovered this fairly quickly and have been hosing the trees down with water and knocking the creepy crawlies to the ground.  But this hasn't solved the problem because every night I come home and there they are again.  Their numbers aren't as high as the first time I saw them but they are still there.  The good news is that these trees have been able to spend all summer getting cozy in their new homes and very soon their leaves would drop anyway so the damage is not hissy fit inducing.  However, they are new baby trees and need all the help they can get and caterpillars stripping them of their leaves could be one step towards eventual demise.  I think I've said this before but any newly planted tree will experience stress the first year it is moved.  This is inevitable.  And any tree, or any plant, under stress will always be susceptible to insect damage.  I'm not a particular fan of chemicals so I'm attempting to deal with this problem in a more holistic way.  First step was to knock the green slimies off the leaves and continue doing so each day.  Next step is to weed around these trees as I've let things slide a bit in that department.  Hopefully a good weeding and raking will remove many of these pests.  Next job after that will be a good soaking of water.  And finally a thick layer of compost out of my compost bin.  The compost will accomplish two things.  First the vitamins and minerals from the compost will slowly begin leaching into the soil below and provide a slow release type of fertilizer for the trees.  That should help build up their strength and make them healthier thereby discouraging more caterpillar attacks.  The second thing it will do is keep the soil below moist so the trees don't lose all that prescious water.  It will also keep the ground at an even temperature.  This is important during periods of freezing and thawing over the winter months.  Soil that has no insulation will react to fluctuations in temperature by heaving and throwing any plant roots up to the surface.  Mulch will help to negate this problem.
They are kinda cute though in their own way
By the way, if anyone is able to identify these caterpillars please let me know.  I think it's best to know the enemy in order to properly defeat them.


  1. What cute little destructive buggers! It sounds like you have a good handle on the problem. I work on a spray them off approach as well. I avoid chemical, and am still a little wary of the one that claim to be safe. Nothing safer than a blast of water!

  2. Yuck! I have very similar worms eating my roses. Here's a handy website for you:

    The second question on the site is about little green worms defoliating a river birch and it sounds like the same problem you're having.

    Good luck! I hope this info helps!

  3. Laura - I agree. Why spray chemicals if it isn't necessary. Personally I think I'm to blame because some of these trees didn't get the watering/mulch they should have. A healthy plant just isn't that interesting to bugs. So why not create healthy plants instead of treating symptoms with chemicals.

    TS - Thank you!! That question led me on a google trail and I now know that these are not caterpillars at all but the larvae of a sawfly (which apparently is a stingless type of wasp! wow) Apparently there is a type that favors roses, so that could be your problem. I've still got some reading to do but this is a great start.