Skeletonizers

What is a Skeletonizer? 

The pest group called “skeletonizers” is a category of worms or bugs that will completely devour the entire green leafy part of a plant leaving only the inner structure of the leaf, the skeleton of the plant if you will.

These are a very destructive creature that is highly traumatizing and sometimes fatal to the plant involved.

Red CurrantTypes of Skeletonizer

The Oak Leaf Skeletonizer is common and affects the Great Lakes Region as well as southern Canada across to BC and northern USA.

The Apple Leaf Skeletonizer is common to the west coast, Pacific Northwest and BC as well as up and down the east coast of North America.

They feed voraciously on Currants, Crab apple, Hawthorn, Cherry, Willow, Birch, Mountain Ash and more. They’ll even eat a raspberry bush given the chance.

Sawfly Larvae in the ForegroundThe pictures show a red currant plant that’s being decimated by Sawfly larva. If left untreated the Sawfly Larva will eat the plant right down to sticks and then it will likely die of stress.

If you have more than one container with a currant plant then it’s good to separate them as far apart as you can in your yard. This way if you get worms on one plant it’s less likely to spread easily to the rest.

As the week went by, the leaf in the picture was completely stripped of all green I was left with just the skeleton of the leaf.

You’ll need an attack plan in place to save your plant from this creature. The best solution is a naturally effective control called BTK. It’s a bacteria that targets worms and caterpillars only. It’s harmless to humans and domestic pets. However, you’ll need a lot of it and do very frequent treatments to eventually stop them.

What is BTK?
BTK is Bacillus thuringiensis kurstaki

Sawfly Larvae on a Red Currant Leaf This is the recommended natural remedy for this and any worm or caterpillar that might be causing issues in your garden. It’s an environmentally sound and natural product. See it here.

It’s sold in a small bottle which is a concentrated liquid bacteria that you mix with water and spray on the affected plants. For large trees the ready-to-use hose-end sprayer is the easiest way to go.

Once this bacteria attacks the worms or caterpillars they die quite quickly. If you have a lot of distance to cover and large area then a backpack sprayer is easiest like the one shown here.

Backpack SprayerIf you have areas that are small square footage or low down then you can get away with a good quality hand held spray bottle.

Chemical Pesticides

Sometimes the natural remedy isn’t enough to save a plant that’s being attacked. When this happens you might need to pull out the chemical pesticide.

A true chemical pesticide such as Malathion should only be used under extreme circumstances and definitely not to be used carelessly. Many locales don’t even allow the use of this product so check your local bi-laws.

Sawfly Larva on Currant LeavesThe reason for the control and reserved use of this chemical is because it kills all bugs including beneficial insects like ladybugs and bees. It’s “non-selective” which means it kills everything, not just the bad bugs that are doing the damage to your garden. This should be a last resort. Its better to do it at night when bee and insect activity is lowest.

So before using a product like Malathion, you’ll need to decide if the plant is worth fighting for to that degree.

If you don’t have an emotional attachment to the plant, then just destroy it, burning it is the best but if you can’t do that then just take good care that the worms don’t drop off on to healthy areas of your garden as you remove it.

Sawfly Larva on Currant PlantDig it up and start with a fresh young plant from a good quality nursery. Sometimes this is a better option to avoid the use of chemicals in the garden. Also, this is a good way to make sure the rest of your garden doesn’t pick up the disease from one sick plant.

If you have a problem as large as the one shown in the images, then you need to pull out all the tools necessary to get rid of them. 

It’s better and cheaper in the long run to add a healthy new plant to your garden than it is to try and heal one single plant because while you are trying to save that one plant, the health of the rest of your garden is in jeopardy.

Skeletonized Raspberry LeafThey’re Back…again

These worms have two hatching cycles per growing season. 

If you keep your eye sharply on the plant in the early spring you’ll see them just emerging and starting to eat. You can kill them before they destroy your whole plant.

After you successfully combat them with your chosen method in the spring, they will show up again around August and repeat the cycle again but even more voraciously.

They are very hard to see at the beginning. They can be hard to see at any size for that matter because they blend in really well, but if you know to what to look for then you will have a better chance of catching the problem early.

Leave a comment and let me know if you have to deal with this pest in your area.

2 thoughts on “Skeletonizers”
  1. I found what looks like an apple skeletonizer on an AZ Yellow Bell its a somewhat transparent shiny green with black spots around each segment. Is that right? Or am I incorrectly identifying this caterpillar?

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