Managing common insect pests

In general garden wisdom, many creatures are just as interested in your veggies as you are. However, there are lots of frustrating bugs that can destroy crops quickly leaving you with little to no return on your vegetable growing efforts. Here are some common insect pests and how to deal with them organically.

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What bugs are eating your garden?

Many gardeners have to battle insects and weeds throughout the gardening season. There are MANY insects that want to eat what you have to offer, some of them can be so destructive the entire plant will be destroyed. In a balanced ecosystem, there would be enough predators to eat these guys. However, in many urban settings, there are not enough of the good predators to keep the balance. Which leaves the job to you!

Most insects have several life stages and not all of them are destructive to common gardening plants. So for some insects and pests, the larval or juvenile stage is destructive but not the adult. Some are destructive through all life stages so it depends on the insect.

A note on pesticides

I am striving to run a pesticide free organic garden that relies more on thorough inspection and removal than any chemical. However, because of this, I tend to lose a few plants (sometimes many).

There are organic pesticides you can use and I’ll cover those for each of the insects below. Remember that any time you employ a pesticide, it is a possibility you will hurt a beneficial (or maybe neutral) insect in you garden.

Squash Vine Borer

The squash vine borer (Melittia satyriniformis) is on of the most destructive pests in my own garden. I have a raised bed vegetable garden in Northwest Louisiana and many pests survive the mild winters quite well, wreaking havoc early in the season and taking down my zucchinis!

The squash vine borer is just as its name sounds. It hatches on the stem or leaf of any then bores into the stem of squash plants feasting on the inner fibers as it gets bigger and bigger. The squash vine borer is the larva stage of a moth that overwinters in the soil near the host plants.

Prevention & Treatment

There are a few things you can do to treat them but one of the ways to prevent them is to practice good crop rotation. This is generally true for most pests and plant diseases. If you keep all your squash in the same bed year after year there is a higher chance that unwelcome guests will find them. Another reason people till in the spring before planting is to disrupt this pupae as well as the hornworm.

Another way to prevent them is put out moth traps and try to catch the adult. Alternatively, you can check the stems and leaves for the small red eggs. They are not always congregating so they can be hard to spot. Once infecting the plant, look for the telltale orangish discharge from the stem of the plant. Even a small amount means a tiny borer could be in your plant.

Related post: When to start seeds outdoors

Squash such as zucchini and yellow squash are particularly susceptible. This year, out of 8 seedlings, none of my zucchini survived because of the squash vine borer. To try to save the plants, I split the stem open and killed the borer then buried the stems. This works better for other squashes that vine but less so for bush-like squash.

Some people inject BT (an organic pesticide) into the stem to kill the borers as a last resort. The bad news about SVB is that there is not a lot you can do to treat once they’ve made themselves known. If they are destroying your plants, you may have to reconsider how and where you grow squash for next year but this year might be a loss.

Tomato Hornworm

Another super destructive insect in the garden is the tomato hornworm (Manduca quinquemaculata). They are a vibrant green caterpillar that simply devours entire tomato and pepper plants in just a few days. They’re usually the color of the tomato plant and reside under the leaves which makes them tricky to spot.

The tomato hornworm is one of the instar stages of the five-spotted hawkmoths which lays its eggs on the under side of leaves of certain plants including tomatoes. The pupae are dormant through the winter underground in a cocoon.

Prevention & Treatment

While the youngest tomato hornworm caterpillars are the hardest to see, they quickly become large enough to see and remove. The are big! Over 2 inches long in their last form and can mow down whole plants. The first signs you have a problem are the removal of leaves. Often the stem of the leave will be left behind.

Look underneath leaves all along the plant but be weary of the stinger at the end of the caterpillar. I take scissor with me (solid big ones, LIKE THESE) and score the leaves then simply snip the caterpillar in half. Its not pretty but it saves the tomatoes.

If you are lucky or can encourage the lives of their parasitic wasp, you’ll be in good shape. If you find a horn worm with the telltale white eggs on its back, try to leave it if you can. This will produce more wasps to help control this pest.

Because they pupate underground, it might be a good idea to till in the early spring to disrupt or remove them as you find them. They are big and brown, I’ve found a few but usually do not till.

Aphids

Aphids are very small insects that use their mouths to suck the sap out of young leaves. They can damage lots of plants by making the leaves wilt, curl and turn yellow. Eventually the leaves will die. They can also feed on fruits and flowers, causing them to be damaged and ruined.

Annoyingly, aphids do not operate alone. They aggregate in huge groups if left unchecked and do work together. The craziest thing about aphids is they have an unusual relationship with ants. At first I though the presence of ants with aphids was a good thing, because they would eat them. While they do consume the aphids what they do is slowly suck a little out of their bodies and work to protect the aphids while they destroy your plants.

Prevention & Treatment

I physically remove any aphids I find. While they are small, since they congregate, you can usually find them (or follow a good trial of ants). Look under the leaves of your plants regularly. I find them most often under the leaves of my fruit trees, the new growth in particular. They are also attracted to the mustard family, which you can use as a trap to keep them away from more valuable crops.

Another method to treat aphids is a mix rubbing alcohol and water. Spray where they are and they will die in reaction to the alcohol. Insecticidal soap is also effective, but it can be considered a pesticide. You can also use diatomaceous earth and neem oil, both are considered organic.

One of the best ways to help keep your aphid population under control is ladybugs. These sweet looking insects actually prey on aphids. If you do not see many ladybugs in your garden, look into purchasing some or even better provide a habitat in which they are welcome and encourage them to take up residence in your yard.

Grub Worms

Grub worms are the larval stage of a few different beetle species. When they are grubs, they look really similar. I find mine when digging up the lawn and I suspect they are the larvae of June bugs which fly around my lights during the summer.

They’re destructive because they eat the roots underground of lots of different plants. They can be particularly destructive to lawns and can cause areas of brown to suddenly show up in an otherwise good looking lawn. But they can also impact a vegetable garden if they are really dense.

Prevention & Treatment

If you have grub worms in your lawn, not in the garden, likely grub worms infestations that actually hurt the lawn are from right waterings. This means that the water isn’t soaking down into the soil long enough. If you have recently converted part of your lawn into a garden space, you may have seen a few grub worms here and there.

First, make sure the way you are watering is best for your plants. A really good heavy soak is good depending on when and where. Then give your lawn a little time to dry again. This drying is key to the grubs not surviving.

The most commonly cited fight against these are beneficial nematodes you can purchase and spray over your lawn or garden. It is an organic pest control based on this predator prey relationship. It is not a pesticide and should not impact other beneficial insects such as earth worms and bees.

I usually find them when the kids are digging in the dirt or when I need to till. They are not usually in the raised beds I’ve built. However, when I do find them I simply feed them to the chickens. Also, the chicken tractor effectively lightly tills the soil and the chickens scratch for these guys themselves.

Leaf Footed Beetles

At first I thought these were “stink bugs” which is a generic term for a beetle that looks similar. Leaffooted bugs (or beetles) are a from a few different species of the Leptoglossus family. They are noticeable by the widened part of their back legs. They also have bright red nymphs that congregate in large groups under leaves of different plants.

They are common in weeds and high grassed but then migrate in groups to ripening fruits in the garden, particularly tomatoes. The most annoying thing about leaf-footed beetles is their piercing mouth parts that damage tomatoes. They suck out the juices and leave behind pock-marks and bacteria causing the tomatoes to be essentially ruined, tough, bitter and ripening incorrectly. They are one of my greatest foes because they change perfectly lovely tomatoes I’ve watched ripen into a mess.

Prevention & Treatment

One of my favorite suggestions for removing these suckers is a hand vacuum! Because they congregate you can get lots of nymphs at once. They are pretty fast once they feel threatened and the adults can fly away very quickly, making them harder to catch. Because they are dark, they are not green like the hornworm, you can usually spot the adults pretty easily. They are about the length of a dime or nickel.

If you do catch an adult, just drop them in a bucket of soapy water and they’ll die pretty quickly. When researching more about them, it turns out most people do not have the issues on the scale that I am having. This might be due to our proximity to large grassy area, a local golf course. However, because I live on an urban homestead, I do not have a lot of plants to spread them out. Thus they concentrate on the 5 (rather than 500) tomato plants I do have.

Make sure you check the leaves for eggs. Then physically remove those as well. And squash any nymph or adult your find. If you are squeamish, use the soap bucket method. Some people have had luck with insecticidal soaps and row covers but this has not been my experience.

The good guys

One quick note about pests. In general, aim for an ecosystem in your garden in which the pests are being kept in control by their natural enemies. Look into beneficial nematodes, earthworms, bees (honey and others), parasitic wasps, ladybugs and praying mantis.

If you can, make sure part of your garden is dedicated to fostering these positive interactions. A big first step is to not use any insecticides. But the very next step should be to allow these insects a home on your property as well. Most insects, friend or foe, need water and a food source. Build a ladybug and praying mantis home from scratch.

What bugs are you battling? Drop me a line and let me know what other pests are out there.

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