Are Caterpillars A Pest For Bonsai?

You may occasionally find a caterpillar crawling around on you bonsai, and while they look cute, they are actually a pest and can be extremely destructive.

If you see one, you have to remove it right away. 

Are All Caterpillars Trouble For Your Trees?

I am pretty sure there is thousands of species of caterpillar, and while some of them may be harmless I think it’s safe to say the vast the vast majority of them are trouble makers.

I would very much take the approach that if you see one, assume it’s bad and get rid of it.

I wouldn’t allow it to hang around to see what it does, as the chances of it upsetting you are extremely high, if hasn’t done so already.

Do They Target Any Particular Type of Tree?

I am not an expert on caterpillars and I am sure some types will target certain types of trees, but I haven’t quite worked out a pattern of what they like.

However, I have noticed my prunus does seems to attract more than the other trees, so it is likely they will target one species over another but I am sure they can cause equal amount so damage to any of your trees given the chance.

I do also think caterpillars are easier to spot on deciduous trees, but they will attack conifers so you should still be checking these trees too.

What Do Caterpillars Do To Bonsai And How Do You Spot Them?

The first and most annoying thing caterpillars do is eat the leaves …and they will eat a lot, quickly.

The little book we all read as kids is not a lie, the caterpillar is indeed hungry and they can quickly smash a tree and basically just eat the whole thing.

You will start to notice round holes in your leaves, or semi circles missing from the edges. This is a classic sign that a caterpillar has made your tree its lunch. 

The second thing they can do is use the leaves as a nest. The caterpillar sort of stands in the middle of the leaf and grabs each side and wraps the leaf around themselves …like a little blanket or a taco. Then they use their web to sort of seal themselves into this leaf nest.

If you notice any of your leaves looking curled up, or two leaves looking stuck together, then have a closer look, as it’s probably a caterpillar.

To be fair at this point they are less harmless, as they are now trying to become moths/butterflies, but either way I doen’t like my trees being used in this way and I will still remove them.

Is This Bad For The Tree?

Luckily a lot of the damage caterpillars cause is superficial. Most trees can lose all their leaves and still be fine. It mostly just looks ugly and is annoying to see lots of holes in your leaves.

However, if you are trying to keep your tree healthy the last thing you need is for a caterpillar to defoliate it for you.

Caterpillars can quickly eat all the leaves and leave your tree bare, which you may not want and for some trees this can be troublesome, especially conifers, but ultimately most trees should survive an attack, especially if you remove the problem before it gets too out of hand.

How Can You Get Rid Of Caterpillars From Bonsai?

The easiest way to deal with caterpillars is to just pick them off and place them on another tree away from your bonsai. They are still an important part of your gardens ecosystem, so it’s best to just try and escort them to an area where they can eat whatever they want …such as your neighbours hedge.

You could also put them in an area that birds will eat them …if you are upset with them. 

However, this is really only possible if there are only a few that need picked off. If you have a huge infestation you are probably going to need pesticides.

Most pesticides say on the box what they will kill, so you just need one that says caterpillars. These are also usually systemic, meaning you water it into the tree and it ends up inside the tree. Now if a caterpillar eats your leaves, it eats the poison.

I have heard people suggest that you just spray them off with water, which I guess would work, but really it’s better to remove them and then you know they are gone.  Water may only just knock them off and then they can climb back up when you go back inside.

Can You Stop The Eggs?

Trying to stop their eggs is probably a little harder to deal with and not worth worrying about.

Since the adults can fly, they can really land anywhere and lay eggs, so they might not even be in your bonsai soil. You the also have the fact that the caterpillars can crawl, so again, they might not be in your soil and may just walk over to your tree from somewhere else. 

I wouldn’t worry about the eggs. I would just worry about when they are actually on your tree and eating your leaves. 

How Can You Prevent Caterpillars In The First Place?

As I just mentioned, it’s hard to prevent them. The eggs can be anywhere and the caterpillars can crawl, so really there is always a risk that they just walk up to your tree and eat it.

It is always going to be easier to just deal with them when you see them rather than trying to prevent them.

I also imagine there is some sort of pesticide that will kill their eggs that you could spread in the area, but you would need to look at what is available in your local shop to see what you can use. I’ve only seen pesticides that kill them once they are hatched and crawling around, but maybe there is a product out there that can.

Conclusion

Hopefully now you understand that while caterpillars are cute, they are extremely destructive and will quickly eat the leaves on your tree.

If you ever see one, remove it and check he has no other friends with him. There is nothing more upsetting that seeing your beautiful leaves covered in bite marks. 

Luckily the tree can always recover and little leaf damage is just cosmetic, but even so, don’t let the caterpillars do what they want, there are plenty of other trees nearby that they can eat instead. 

(You can read more about – Ladybirds On Bonsai)