Master Gardener: How to tell what is eating the vegetables in your garden

One of the difficult parts of being a vegetable gardener is realizing that, yes, you are growing food for you and your family, but at some point, you realize you are growing food that a lot of other critters want to eat, as well. Food is food… right?

We like to know what particular insect is dining on our plants. However, if you can’t find it, you can narrow down the possibilities by looking at the type of damage being done to your plant.

Insect damage to our plants tends to come from three types of insect mouth parts: chewing, rasping and piercing-sucking. Holes in the leaves would indicate that it is an insect with chewing mouth parts, but there are a variety of those. So, next you need to look at the shape of the hole.

If the edges of the hole or damage have ragged or jagged edges, it’s likely a beetle of some sort. If the chewing damage being inflicted has more of a rounded edge or perhaps even a nicely chewed hole, it’s probably a caterpillar of some sort.

Now that you know, you can make a better decision on how to approach the issue. First of all, you always have the option of doing nothing. Not every gardener can do this, but many gardeners approach the vegetable garden with the attitude that they are growing some for “me” and some for “them.” If this is not your personality or perhaps, they are destroying everything, you have some options.

About the most environmentally friendly, organic thing you can do is to remove the insect by hand. This involves picking them off the plant or perhaps squishing them in place. Again, this will not be the first choice for some of you.

Fortunately, we have some good organic pesticides that are available. If the chewing damage indicates a beetle of some sort, Spinosad or Pyrethrin are both good organic pesticides. If the chewing damage created is a more circular hole, it’s probably a caterpillar of some sort. You can treat for caterpillars using another organic pesticide called bacillus thuringiensis. Bacillus thuringiensis is only effective on caterpillars, so you don’t need to worry about any collateral damage the using this product.

As is true with anything you choose to spray on your garden, be sure to read the directions on the label. I know this is not our favorite thing, but different manufacturers may use the same ingredients but in a different strengths, so it’s important to know how to use it properly.

Also, when reading the instructions, be sure to pay attention to what is called the pre-harvest interval. This refers to the number of days you can safely use this product before harvest. The good thing about most organic pesticides is that they have a shorter pre-harvest interval. Some of them even say you can use up to the day of harvest.

In contrast, the synthetic pesticides tend to have longer pre-harvest intervals. For some crops, the pre-harvest interval for a synthetic pesticide can be two or three weeks. This is important for obvious reasons, and it underscores why you need to be informed about the products you choose to use in your garden. Good luck.

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