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May 29, 2009 05:44 AM

Caterpillar Help!

Hello all!

I'm a newbie gardener with a very newbie garden (when I moved in last year, the yard was overrun with litter and weeds). I put in a small vegetable and herb garden, and a small flower garden. Everything seems to be doing well, but this morning I noticed that all the leaves of my radishes have been chewed through, and the leaves that are left have dark green bumps and small green caterpillars on them. I'm trying to be as nature-friendly as possible, and I don't want to kill anything that could be benign or even useful in the garden. What category are these little caterpillars in? So far it looks like the radishes are the only things they've attacked, but are my other plants next? And if I should get rid of them, what's the best way?

Thanks for your help!

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  1. Hi, I did a quick search for radish pests and didn't see anything about little green caterpillars; no ideas on what they might be. When I have something eating specific plants, I have had good luck with hand picking and dropping them into soapy water. I have had little green caterpillars on columbine... they match the leaves so well they are really hard to see! I also hand pick those horrid little red lily beetles. This year, so far, so good, but I will spray if I have to.
    Maybe you could search on general garden pests and see if you see your caterpillars?

    1. From a gardener's point of view there is no such thing as a benign caterpillar. All they do is eat plants that you were planning to eat later. However, they are rather specific in their diets. A species that feeds on radishes is not going to grow up to a butterfly or moth that will lay eggs on a bean plant. But if you do nothing you could lose most of your radishes in short order.

      Fortunately there is an excellent non-toxic way to control a wide variety of caterpillars. It's bacillus thuringiensis or BT for short. Spray it on your plants, the caterpillars eat the bacterium, and they die a horrible death. The Safer brand sells it as "Caterpillar Killer". But if you just have a row or two of radishes that are being attacked you might as well pick them off like ccrow suggests.

      2 Replies
      1. re: Zeldog

        Yes, avoid BT unless you have a really serious infestation and the caterpillars are causing more damage than just to your radish leaves. (Radish leaves are expendable!) BT is nontoxic, natural, and an excellent way to kill caterpillars, BUT it kills them all -- including the ones that will turn into harmless moths or butterflies.

        So only use it if you have to. If you can control them any other way, do it so as to minimize the impact on your little ecosystem.

        1. re: mudster

          Radish leaves are expendable? Well now, I would love to grow a radish that didn't need leaves to produce an edible root, but it doesn't work that way. But for BT to work the caterpillar needs to eat some of the plant, which means it does not kill harmless bugs (if you define harmless bug as one that doesn't eat your plants). That's why I really like the stuff. The BT I sprayed on my broccoli and tomatoes is not going to kill any monarch butterflies because they are out looking for milkweed or whatever, but the cabbage moths and hornworms must die.

      2. Thanks for the advice! I just scooped up the whole area of radishes, along with the caterpillars and their eggs. I have more radishes in another spot, and I figured I shouldn't risk leaving any of those eggs behind. I'll look into getting some BT so I can be prepared for another attack!

        1 Reply
        1. re: agoldman

          Hi all, I have the same problem. All my plants were doing great, until one day I noticed a green caterpiller wrapped up in the new growth of the olive tree. The next day, there are five in the lemon tree's new leaves. The next, they'd invaded the basil, the strawberries and the red leaf lettuce. I picked them all out by hand, sprayed the plants with a mixture of Dr. Bonner's, water, and cayenne pepper, but ack, they are back. Now I want to get BT on the whole garden before the little green munchers eat all the food we wanted to eat! But alas, I can't find any in any of the garden stores in SF. Any idea where you can get the stuff? Even Lowe's and Home Depot said they don't have it.

        2. What you have is cabbage moths. I just hand pick mine when I see them. Wasps are a natural predator, so don't worry if you start seeing them all around your plants and leave them be if their nests aren't in a high traffic area. If you can't stand the thought of touching them and don't want to wait for the wasps, you can always put a bit of dish soap in a little spray bottle of water and spray them directly. I always save BT as a last, last, last resort.