Problem Pests in Outdoor Gardens

Are your tomato leaves disappearing? Is your squash wilting and dying even though you water it? Your garden shares space with a plethora of insects and wildlife, some of whom might find it a tempting meal. Here are the pests we have encountered and how we kept them from getting out of control.

Tomato Hornworms

You walk out to harvest tomatoes one morning and notice that a branch on your tomato plant has been stripped of leaves practically overnight. Looking under the plant, you see a scattering of greenish pellets - caterpillar poop. It may even appear as someone has taken a large bite out of your tomatoes. If you look closely, you'll find one of these green guys - the giant larva of five-spotted hawk moth.

Image courtesy of Texas A&M AgriLife.

These things are huge and I swear you can hear them crunching. But believe it or not, they are manageable. Here is how we deal with them:

1) Follow their trail. Find an area of the plant that has been affected and trace the branch until you spot the caterpillar. You'll have to look closely, as they match the color of the plant perfectly. Then simply pluck the caterpillar off and put it in a bucket of water or better yet, feed it to your chickens if you have any! We've been able to control a hornworm population just by removing them by hand like this.

2) Let the wasps do their work. If you see a caterpillar with rows of white egg cases along its back, DO NOT KILL IT. You can remove it from your tomato plant to prevent further damage, but place it somewhere else away from your garden. This hornworm is the victim of a parasitic wasp. When it's eggs hatch, the hornworm will die. You'll want to keep these wasps around and use this type of biological control to your advantage! 

3) Treat the plant with Bacillus thuringiensis. This organic treatment is another form of biological control. The bacteria in it will kill the hornworms and prevent further infestations. You can purchase it here.

Flea Beetles

Are your eggplant leaves starting to look like lace? The small holes may be caused by a tiny black flea beetles. They get their name because of the way they hop around the leaves like a flea. While we have never had an eggplant actually die from flea beetle damage, it certainly weakens the plant and reduces production. We have found yellow sticky traps with flea beetle lures to be effective at getting the situation under control. 

Flea beetle damage on eggplant

Cabbage Worms

Those beautiful little white or brown moths seen flitting around your garden are probably a sign of problems to come. They are laying eggs on your brassicas - kale, broccoli, cabbage, etc. When those eggs hatch, the larva will eat their way through your entire crop. There are a number of moth species that do this and the larvae can range from bright green to gray and black. There are a couple of ways to ensure that you won't have to pick worms off your brussel sprouts come harvest time.

Cabbage worm damage on kale

1) Use a physical barrier. We love these mesh tunnels for keeping moths from ever reaching our plants. They are so easy to install and even shade these cool-weather plants, allowing us to continue to harvest come warmer weather.

Cabbage with row covers

2) Spray with a biological insecticide. Mix up some Bacillus thuringiensis in a handheld sprayer and douse all sides of your plants. This organic treatment is very effective at killing the worms once you spot them.

Squash Bugs 

At quick glance, it may look like your plants are wilting or suffering from a fungal infection. Upon close inspection however, you might find gray insects which look like stink bugs crawling along the vine. If you turn over a leaf, you'll see their white and black babies, called nymphs. They'd almost be cute if they weren't so destructive.

Squash bug adult on cucumber

Squash bug nymphs on cucumber  

Squash bugs target plants that are members of the curcubit family - melons, pumpkins, squash, and cucumbers. These insects actually inject a toxin into the plant and suck the nutrient-rich liquid right out. The damage compromises the flow of nutrients to the affected leaves causing them to shrivel up and die. 

This pest can be prolific and hard to kill. We tried AzaMax, spinosad, insecticidal soap, and diatomaceous earth individually to no avail. What we found to work was using spinosad in concert with pyrethrin. Each of these organic insecticides has a different mode of action that seem to be effective on multiple life stages when used together.  After treating, keep an eye out for clusters of metallic bronze eggs on the undersides of leaves. You will need to retreat when these hatch.


Deer, Rabbits, and Squirrels

(and free-range chickens)

You can install an inexpensive fence to keep wildlife at bay, utilize a pest deterrent spray, or even build a simple frame over your raised bed and drape it with netting.  But by far the most entertaining way to scare off would-be thieves, is with a motion-activated sprinkler

Motion-activated sprinkler wildlife deterrent for garden

We LOVE this thing. When our flock of 30-something chickens kept jumping the fence to scratch and dust-bathe in our raised bed gardens, I found myself running outside to squirt them with the hose every 30 minutes. Eventually they wised up and only hopped the fence when I wasn't around. I needed something to scare them off in my absence. Enter the Orbit Yard Enforcer

IT SAVED MY GARDEN. With range adjustments, day and night modes, and water-saving features, you can truly customize this sprinkler to your situation. After a few weeks of use, the chickens stopped attempting to get in our gardens and months later, they haven't been back. Now I use it to keep the goats away from a grove of trees that I don't want them eating. It is very effective. And hilarious to watch in action!


For a complete listing of products that we recommend, visit our Pest Control Collection.

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