Saturday, June 11, 2011


Our rooftop tomatoes are suffering from the effects of a caterpillar infestation.

Tomatoes bitten by caterpillars

If we had been a little more proactive, we would have seen the signs of this, before this much damage had occurred but there is still time to save the rest of our crop.

Caterpillar poop on leaves

By carefully inspecting your plants daily, as we should have done, you should start to see caterpillar poop before they cause significant damage to your plants. You will also see damage to the leaves, by way of holes eaten through them. Where there is caterpillar poop, there are surely caterpillars nearby.

When you see these signs, you can start hand picking the pests and likely get them under control. They hide during the day so the best method for finding them is at night with a head lamp so you have your hands free to pick them off and dispose of them.


Caterpillar Cocoon
We normally do not like to use sprays to control pests in the garden because even the "organic" sprays can have a negative effect on beneficial insects. There are some other things you can do to help control them as well. Planting other plants that they like can help keep them away from your vegetable plants, some of those include; butterfly weed, flat leaf parsley, fennel and dill. We don't have any of those in the garden but we do have an ornamental vine called an orange beauty that caterpillars gravitate to for easy hand picking at night.   

Unfortunately there are times when you may need to use something other than hand picking to control a destructive insect though. When we choose to use a spray, we only use products that have the OMRI logo on them. In this case, we decided to pull out our Safer Brand Caterpillar Killer. The main ingredient in this product is Bacillus thuringiensis or BT.

Safer Caterpillar Killer
If you do decide to use a product like this to help you control destructive insects, you want to mix it according to the instructions, and then spray it when it's cool outside. Please do not spray this product if there are any bees or other beneficial insects present. 

After you spray, you can go back to hand picking at night, to try and get control of the problem but in some cases, another application may be necessary. 

Gidget says; "You should have been on top of this problem sooner!"

1 comment:

  1. Caterpillars can be a real scourge in the garden! But I agree with you, Crystal--hand picking is the best and safest method of controlling these pests. I have also used BT, and it's very effective, especially in controlling tomato hornworms and Cabbage white butterfly caterpillars. Since we have bees, I'm really hesitatnt to use BT, but I may use it very, very judiciously on the brassicas and tomatoes...only a small amount, and most likely just one time. As you said, even the "safe" sprays do have negative impacts on beneficial insects, and I won't do anything to harm our honeybees! I also worry about BT having a negative effect on all butterflies, and that really makes me think twice before I decide to use it. I've seen quite a few Cabbage whites fluttering around my brassicas, so it may be time to give just one small application of BT to those plants. Otherwise, they could be completely decimated by those Cabbage white caterpillars!