Not all creepy-crawlers are welcome in the garden, but some insects are very beneficial to the success of your flowers, herbs and veggies. According to Almanac, beneficial bugs fall into three categories: pollinators, which help pollinate plants; predators, which feed on garden pests; and parasitizers, like parasitic wasps and other insects that lay eggs inside of harmful insects.
Many beneficial bugs can be bought from nurseries and introduced to your garden, but creating a welcoming environment will convince them to come of their own volition. A diverse, well-mulched garden full of native flowering plants is a haven for these good bugs. Because pesticides — both natural and synthetic — are indiscriminate in what they kill, raising an organic garden is also crucial for attracting beneficial bugs. If the right insects are there, then they’ll deal with all of the aphids, whiteflies and other pests for you.
Here are a few insects that you should welcome into your garden, and how to get them to stick around all season.
It’s no secret that earthworms are a garden’s best friend. Because these squirmy invertebrates breathe through their skin, they find oxygen by tunneling through the soil, creating pockets of air in the process that hold both water and oxygen for plants to use, too. Their movement also loosens the soil and makes it easier for roots to grow. As they tunnel, earthworms break down dead plant matter in the soil, making those nutrients available for your growing garden. Their excrement — called “worm castings” — is also full of beneficial nutrients like magnesium, nitrogen, phosphorus and potassium. Worms themselves are an important source of food for birds, which also combat garden pests.
It’s likely that there are already worms in your garden (unless it’s a completely new space), although they can be easily purchased from garden suppliers. To attract those already in the ecosystem, give them something to feed on, like leaf litter or your home compost mix. Worms don’t like compacted soil and tend to avoid ground when it’s wet and more readily compacted. Avoid tilling the garden, too, which can disrupt their habitat. To make the soil more hospitable in the winter, plant a cover crop that will help regulate soil temperature, nutrient content and moisture during the colder months.
The darling of the garden, ladybugs are known for their voracious aphid-eating capabilities (a single bug can eat up to 40 aphids every hour), although they’ll feast on a variety of pests, including mealybugs and mites. With their dark color and orange spots, ladybug larvae look threatening at first and can easily be mistaken for a garden pest, so take a better look before you squish them.
To attract ladybugs to your garden, grow plants with flat flowers or those in the parsley family like carrots, fennel, dill, parsley and yarrow, as well as marigolds and calendula. If you buy ladybugs from a nursery, resist the urge to put them in the garden right away — without a source of food, they’ll fly away. Put the container in the fridge for 6-8 hours before releasing them. This slows them down so they don’t fly off when you open the container. Release the bugs at twilight or right before dawn somewhere in the yard that has flowering plants or aphids for them to eat.
Praying mantises are ravenous eaters of aphids, caterpillars, mosquitoes and invasive spotted lanternflies — but they’re also likely to go after other beneficial insects like beetles, butterflies, and bees. Therefore, they’re best used in yards with a significant pest problem, since they’ll have plenty to snack on besides pollinators and other pest-eaters. If you have a pollinator garden, it’s best to skip them entirely rather than risk losing the local pollinator population.
To introduce the mantises, buy egg cases from a garden center, which you can keep in the refrigerator for a few weeks until it’s warm outside. When releasing them, don’t place the container on the ground, where hungry ants might go after the eggs. Instead, hang the container from a tree in a shady spot, preferably somewhere near pests so the praying mantises are encouraged to stick around.
Aptly named, lacewings have bright green bodies and delicate looking, lace-like wings. Their larvae are predators of many insects, including aphids, caterpillars, cabbage worms, mealybugs, mites, thrips and whiteflies. Lacewings also tend to stay close together, which is good for dealing with a concentrated pest problem. They can be bought and introduced, but lacewings will usually come on their own, hanging their eggs from threads on the underside of leaves. To attract them naturally, avoid pesticides, which will kill them off. Pollinator-friendly plants will encourage the adults — who feed on nectar and pollen — to stay in your garden all season.
Yes, Japanese beetles, Mexican bean beetle larvae, and Colorado potato beetles are bad news — but not all beetles are created alike. Ground beetles are a group made up of 2,500 types of beneficial beetles that crawl on the ground. These nocturnal insects dig into the dirt during the day, but will come out at night to feast, which makes them especially helpful for tackling pests that are active at night, like slugs. They eat more than fifty different pests, including snails, nematodes, caterpillars, thrips, weevils and silverfish. Keep in mind that they can’t climb, so they’re limited to eating the species that live near the ground.
Ground beetles live in decaying plant matter. To attract them to your garden, mulch the surface, and they’ll happily overwinter there. They also live in perennial plants that provide them shelter. If you want to introduce some to your garden beds, turn over a few logs and they’ll almost certainly scurry out, and you can transfer them to the garden yourself.
Also known as leatherwings, soldier beetles are part of the family Cantharidae, which has nearly 500 species. Their orange and black bodies make them look menacing at first, but they’re actually very helpful as both pollinators and pest predators.
Soldier beetles pollinate while feeding on pollen and nectar, but they also eat other insects, including the eggs of grasshoppers and soft-bodied insects like caterpillars and aphids. Like ground beetles, they live near the soil (often under logs) and like some cover from leaves and mulch. To welcome them into your garden, plant flowers with compound blossoms like Queen Anne’s lace, and those with yellow and orange blossoms like marigolds and zinnias.
Wheel bugs and ambush bugs are among the most common assassin bugs, but there are 150 different species in North America alone. Both the nymphs and adults will eat pests, making them a welcome addition to the garden.
Assassin bugs have a distinctive curved, beak-like mouth (called a rostrum or proboscis) that they use to spear their prey, injecting venom into their body and then sucking on the insect to feed. They’ll eat aphids, boll weevils, caterpillars, leafhoppers and even some insects larger than themselves. Assassin bugs can generally be found in bushy plants or weed-filled areas during the summer. Unlike some other beneficial bugs, they aren’t readily available for purchase, but it’s good to know what they look like so you don’t eliminate them by accident.
A good garden needs pollinators, and bees are one of the best. About 80% of all plants on earth depend on pollinators to survive — they’re crucial to the growth of many herbs, vegetables and flowers, probably including many in your own garden. It’s important to note that not all bees look the same. Bumblebees and honeybees are familiar, but there might be other native bees in your yard that don’t immediately look like the pollinators we know and love.
To attract bees to your yard, give them plenty of native flowering plants to feast on. Because clover, dandelion, and other lawn weeds are important food sources for bees, mowing your lawn less frequently will give them another source of food. Bees need water, too, and a small bowl of water filled with marbles gives them somewhere to drink without fear of drowning. Solitary bees (those that don’t live in hives) create different nests, and their nesting sites should be protected. Ground nesting bees create holes in the ground, while cavity nesters look for debris like branches and logs to make their home, so they’ll be happy if you leave some yard and tree trimmings untouched.
Unlike some other wasps, parasitic wasps like brachonid and trichogramma wasps are very small and don’t sting. They’re identifiable by what looks like a stinger, but is actually an ovipositor, through which the female lays her eggs inside an insect -—including aphids, caterpillars, and stink bugs — and the young then eat their way out. The adults feed on pollen and nectar, so a garden full of flowering plants will attract them naturally.
This article by Linnea Harris was first published by EcoWatch on 12 May 2023. Lead Image: Ladybugs contribute to a healthy garden by feasting on a variety of pests. ds3ann / Imazins / Getty Images.
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