Managing insects in the garden, naturally

One of my favorite things to do is find a spot to sit right in the heart of my garden. It is especially a pleasure during the late summer days as the plants are full, the fresh pungent smell of ripening vegetables fills my nose and I hear the hum and buzz of insects doing their life work.

A large green hornworm climbs a plant stalk.
Naughty little hornworm.

Just the other day, as I was “zenning out” in my garden, my gaze caught a glimpse of a tomato hornworm! My “zenning out” turned to freaking out as I noticed the devastation that had already taken place. My partner and I spent the next 2 hours scouring the plants handpicking close to 40 of the big worms.  I was hoping to find at least one with parasites attached to it but was not that lucky.

(Side note: If you find a hornworm with what looks like a bunch of rice grains attached to its body, the braconid wasp has taken over! These parasitic wasps will kill hornworms once they hatch and go on to infect more hornworms.)

Throughout the season it’s helpful to keep track of the good and the bad within the garden. If the task seems daunting and bug identification seems impossible—start small.  There’s a very small chance that you will lose everything if you try to identify just one problem at a time.

I try to look at things at least once a week, jot down notes, and take pictures if necessary. This helps me form a plan of action to take once I have the time to do so.  Keep in mind that your local extension agency is always there to help. Once you figure out which gremlins are doing the most harm, there are quite a few remedies to try out!

Check out this Pest and Disease directory Gardener’s supply has created.  

Prevention Techniques

Build healthy soil. Healthy soil equals healthy plants. Healthy plants equals less pests! Keep up on testing your soil and amending as necessary so that your plants are nice and healthy. Make sure to add plenty of organic matter to retain moisture and give a home to our friends, the decomposers.

Decomposers help break down organic matter and provide plants with usable nutrients.  Pesky insects are often attracted to unhealthy stressed plants so keeping your plants happy will also help to keep them bug free.

Man holding a bunch of plants he has cut from the garden.
Nick is a great garden groomer!

Groom your garden. Make sure to keep up on weeding and disposing of diseased or infested plants. All the above give home and food to unwanted pests. Also, try to be clean yourself—unwelcome pathogens and bugs can be easily spread by you and unknowingly. I once picked a leaf that was infested with aphids and the next thing I knew it wasn’t in my hand anymore—I’m sure they found a new home soon enough 🙁 

Rotate your crops. It will be helpful to rotate where you plant certain vegetables year by year. Not only is it good for allowing plants to get a wider array of nutrients, but it can confuse the pesky insects who may have overwintered in the soil below. Also, planting smaller sets of plants throughout the garden instead of planting all of one crop in one location will help lower the chance of an infestation.

Watch when you water. Get in the habit of watering early in the day. This will help foliage dry out during the rest of the day. If you have the means to do so, installing drip irrigation not only helps keep foliage dry, but it also saves time and water in the end. Wet foliage encourages insects to come to your plants.

Plant deterrents. Planting herbs and flowers within your regular plants can help deter certain pesky insects. Every year, I plant basil around my tomatoes as it is supposed to help with whiteflies, spider mites, aphids, and mosquitos. Next year, I think I’ll try to grow borage around the tomatoes as well since we had such a problem with the hornworm and borage naturally deters those worms.

Encouraging Beneficial Insects

Support the “3 P’s and a D” of beneficial insects. Predators, parasites, pollinators, and the oft-forgotten decomposers are what makes the garden insect circle go ‘round!   

  • Predators are generally insects who eat a variety of other insect species. For example: ladybugs eat aphids, leaf hoppers, mites, and mealy bugs. Praying Mantis eat larger bugs like moths and adult grasshoppers.
  • Parasites find a host and lay their eggs on or inside that host. Such as the braconid wasp I was hoping to find when we were scouring our garden for hornworms. The braconid will lay their eggs on the hornworm.  Another helpful parasite is the leaf miner parasite. This is a tiny parasitic wasp which kills leaf miner larva in the mine and lays an egg on it.
  • Pollinators are what allow flowering plants to produce their fruits and seed. Honey bees, butterflies’ wasps, beetles, flies, and the hoverfly are all important pollinators.
  • Decomposers help break down garden waste and turn it into nutrient rich soil which plants can then use. Decomposers are often microscopic but by no means does this make their job less important. Keep a healthy amount of organic matter like compost in the garden!

Keep good bugs happy: Build an insectary. Create food and homes for beneficial insects. Plan to use at least ten percent of your garden for plants that these insects love! It’s important to keep planting through the season so that insects stay around to help. For instance, you can plant cilantro and radishes for late spring blooms; Dill, fennel, and buckwheat for early summer blooms; Borage, thyme, and sunflowers for mid-summer blooms; and catnip, mint, and oregano for later summer blooms.

Check out this Mother Earth News article with an amazing list of annual and perennial plants to keep in mind when creating your insectary!


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