Now that it’s Summer, insects are out in full force and there’s no better place to observe them than in the garden. Now, before you feel the dread sinking in, remember - if you are gardening in a way that is good for the Earth, you will have your share of insects. While there are organic pesticides (some of which we’ll recommend below) the most interesting and least harmful way to keep your pests at bay is to attract other animals (often other insects and birds) that will eat them!
While we want to create healthy ecosystems that attract beneficial insects, it can be difficult to recognize which bugs we want to get rid of and which we want to keep around! Here’s a quick guide of a few of the most common pests and beneficial insects that we see. Stay tuned next month for more!
Aphids - Aphids are tiny insects that hide in mass on many different crops, feeding on plant sap. They come in a wide range of colors but are usually found in large groups on the undersides of leaves.
Fun Fact: Aphids have a mutualistic relationship with ants. Ants “milk” aphids for their nutrient rich secretion (known as honeydew) while aphids benefit from the protection of the ants. If you find ants on your crops, chances are there are aphids hiding there too!
Flea Beetles - Flea beetles are small leaf beetles that feed on the foliage of many common garden crops including beans, eggplants, potatoes, peppers, tomatoes, and more. Their larvae live underground and are known to feed on roots and germinating seeds early in the season. The beetles tend to be small, black or brown, and may have white, yellow, or orange stripes on their wing cases during some stages of maturity.
Fun Fact: Some species of flea beetles are currently being used as biological controls to combat the introduction of invasive weeds that are toxic to most other herbivores. (Look up leafy spurge!)
Cabbage Loopers - Cabbage loopers get their name from their food preference. Although they will snack on most crops, these caterpillars will devour anything in the cruciferous family, including cabbage, broccoli, cauliflower, and kale. These caterpillars are lime green and move by arching their backs much like an inch worms (this is why they’re referred to as “loopers.”)
Fun fact: Although Cabbage Loopers prefer cruciferous veggies, they are generalists and can eat nearly any plant. They can thank their extremely sensitive saliva for this - depending on the plant the looper is eating, its saliva expresses different proteins to break down that plant’s chemical defenses.
Practice cultural and physical controls like crop rotation, planting “trap crops,” companion planting with marigolds and fragrant herbs, and using row cover
Create healthy habitats for beneficial insects (see more about this below!)
As a last resort, use a natural pest repellent such as BT, neem oil, insecticidal soap, or garlic spray. Read the directions carefully to ensure that you are applying properly and targeting only the pest in question.
Ladybugs - Not true bugs but rather beetles, Lady bugs are revered for their great appetite for aphids. Ladybugs are said to eat up to 50 aphids in a day, or 5,000 aphids in their lifetime! Ladybugs, classically, are bright red or orange with black spots, although larvae are have elongated, soft, black bodies with orange spikes!
Fun Fact: Ladybugs are thought to have been named for “Our Lady Mary” - the virgin Mary - who was often depicted wearing a red cape.
Assassin Bugs - Assassin bugs have a famously long and sharp proboscis that they use to inject their prey with saliva. This saliva liquifies the insides of the prey which can then be sucked back up as a nutritious snack. Assassin bugs have a wide range of favorite foods and are known to be able to attack and eat insects much larger than themselves. While varying in coloration, you can recognize assassin bugs by their small heads and long “necks.”
Fun Fact: Assassin bugs are known to attach the empty corpses of their prey to their backs. It’s thought that this provides the bug with camouflage and protection.
Hummingbirds - Although they aren’t insects, hummingbirds are extremely beneficial in the garden. You may know that they drink nectar to maintain their high metabolic rate but the rest of their diet is composed of small insects. One of their favorites is the spotted wing drosophila that is known to plague raspberries. In addition to their help maintaining pest populations, hummingbirds are important pollinators. Hang hummingbird feeders and plant their favorite flowers, like native honeysuckle, to attract hummingbirds to your garden.
Fun Fact: To conserve energy, Hummingbirds fall into a hibernation-like torpor at night. Their body temperature drops from 40 c to around 18 c and their heartbeat drops from over 1000 beats per minute to under 180 bpm.
Attracting beneficial insects:
Avoid immediately killing off their food source - although it sounds counter-intuitive, if you keep those aphids around for a little while the ladybugs will come and take care of them. It you spray to get rid of the aphids, not only will you discourage ladybugs from coming, the spray may affect other beneficial insects.
Provide a secondary food source - when not eating pests, many of these insects enjoy drinking nectar from small, shallow-blossomed, and tightly packed flowers including yarrow, dill, angelica, alyssum, lemon balm, mint, and thyme.
Mulch, incorporate perennial plants with a lot of foliage, or install a “bug house” to give your beneficial insects a safe and warm place to over-winter.