“If there’s a world here in a hundred years, it’s going to be saved by tens of millions of little things.”
— Pete Seeger
Natural predators in the garden are our least expensive, most time saving and most effective tool to keep pest populations in check. These beneficials in the garden are a total win-win for gardeners. They cost us nothing. They free up our time in the garden. And they work to annihilate pests. Jeopardize them with the use of broad-spectrum pesticides and you WILL inherit their work.
All creatures eat
We all need to eat, so many creatures nourish themselves in gardens. Some love to feast especially on roses. These creatures are neither “good” nor “bad” but, since we rosarians don’t like anything that damages and violates roses, we call the creatures that do “pests.” Rose pests in the spring include aphids, rose slugs, caterpillars, hoplia beetles and thrips. Caterpillars, rose slugs, grasshoppers, spider mites and chilli thrips are the prime pests in the summer.
Lions and pirates and assassins. Oh my!
Many of the creatures that come to our gardens are not looking to nourish themselves with plants. They are here to savor and devour the pests of the spring and summer rose garden. To rosarians, these predatory creatures — which include insects, birds, amphibians and spiders — are the white knights of the garden.
Keep reading and you will discover that to their prey, some of these hungry marauders are the stuff of the very scariest sci-fi nightmares. Ravenous and in search of a feast, they bypass gardens where pesticide use has left only a scarcity of eats.
Lay out the welcome mat
To avoid pest infestations and plant stress, gardeners are watchful for the first sign of pest damage. We squish aphids and rose slugs with our fingers, we drop beetle pests in a bucket of soapy water, and we use jets of water to blast off aphids, spider mites and other pests from our roses. The pests that we miss are the “good eats” that entice the hungry good guys (who outnumber the bad guys) into our garden. Good gardeners provide water and grow a diversity of pollen- and nectar-rich plants. Suitably wooed, our friends move in. Our garden becomes their home, and they repay us by keeping pest populations in check.
A spotlight on some of our garden’s favorite friends
Lady beetles are one of the most common predators in the rose garden. There are thousands of lady beetle species with many coloration patterns. Both the adults and their strange-looking orange-black, crocodilelike larvae are voraciously hungry for aphids and other soft-bodied pests in the rose garden.
(Rita Perwich)
Lady beetle larva
(Rita Perwich)
Ladybird beetles (Order Coleoptera)
Everyone’s favorite, lady beetles are one of the most common predators in the rose garden. Usually depicted as red with black spots, in fact, there are thousands of lady beetle species with many coloration patterns. Both the adults and their larvae are voraciously hungry and can “put away” 60 aphids in a day. They also prey on soft-bodied bugs and larvae, including mealybugs, scales and spider mites. There are four metamorphosis stages. The female lays clusters of 10 to 30 yellow eggs under leaves near their food source. The eggs hatch in three to five days, releasing strange-looking orange-black, crocodilelike larvae. Four weeks later, the larva forms a hard shell and pupates, emerging as an adult five to seven days later. Adults overwinter in masses in leaf litter.
Ground beetles are predators of mainly soil-dwelling pests, including snails and slugs.
Rove beetles are mostly soil dwellers and feeders, but some feed inside flowers on soft-bodied insects such as thrips and aphids.
Soldier beetles are flat, slender, elongated beetles that feed on aphids and other soft-bodied insects, grasshoppers and fly larvae.
A lacewing
(Rita Perwich)
Lacewings (Order Neuroptera)
These slender, delicate insects have large, transparent membranous wings with green veins. The adults feed primarily on pollen and nectar in flowering plants and aphid honeydew. Pale green eggs are laid in clusters near the food source with each egg suspended at the end of slender silken threads attached to the undersurface of a leaf. Eggs hatch in a few days, and the alligatorlike larvae are appropriately nicknamed “aphid lions” because aphids are their favorite prey. The larvae also consume other soft-bodied prey, including mealybugs, scales, chilli thrips, thrips, leafhoppers, and spider mites and their eggs. After feeding for two weeks, the larva spins a cocoon to pupate. The adult emerges five days later. Lacewings can overwinter as adults but usually do so as pupae.
Minute pirate bugs (Order Hemiptera) aka ‘true bugs’
Minute pirate bugs measure only ⅛ inch, so they are easily missed. Silver and black, the body pattern resembles a pirate’s skull and crossbones. The wingless nymphs are also predaceous. Minute pirate bugs have sucking mouthparts and suck body fluids from their prey. These heroes are our greatest weapons in our fight against chilli thrips. Mites, thrips, aphids and some pollen and plant juices round out their diet. We can attract them into our garden with small flowers, including coreopsis, verbena and nemesia. They are active in our gardens from April through October and overwinter as adults in leaf litter.
Damsel bugs are slender and tan-colored and have slightly raptorial front legs. These bugs and their nymphs are inordinately fond of spider mites and their eggs.
Big-eyed bugs have a crescent-shaped head and bulging eyes. They are general predators, piercing their prey and draining them of body fluids. Their diet includes aphids, caterpillars, mites, whiteflies and insects’ and mites’ eggs.
An assassin bug
(Rita Perwich)
Assassin bugs are about ½ inch in length, slender and hourglass-shaped with narrow, elongated heads and long legs. They patrol our rose gardens, stalking their prey or lying in wait, to feed on aphids, leafhoppers, caterpillars and flying insects. Prey are injected with venom and drained of body fluids.
Predatory stink bugs are shield-shaped predators and can discharge a foul odor when disturbed. Both nymphs and adults suck the body fluids of their prey, which include caterpillars and insect larvae. Adults overwinter in leaf litter and emerge in spring to devour prey.
Hoverflies (Order Diptera, Syrphidae family)
Adult hoverflies or syrphid flies resemble wasps in appearance, but unlike wasps, they possess the ability to hover. The adult hovers over flowers and feeds on nectar. The tiny, white cigar-shaped eggs are laid on leaves close to aphid colonies. The egg hatches in two to three days, releasing a light green sluglike larva that has a white stripe on its body. The larva feeds voraciously by lifting each aphid and sucking it dry. Each larva can consume up to 400 aphids in the two to three weeks before it pupates. Larvae also feed on chilli thrips, thrips, scale, small caterpillars and other small larvae. The pupa forms a hard casing and drops to the soil. It either emerges as an adult one to two weeks later or overwinters in the soil.
A tachinid fly
(Rita Perwich)
Tachinid flies resemble houseflies in appearance. The adult lays its eggs on the hosts, which include spiders, centipedes, millipedes, caterpillars and, sadly, also monarch caterpillars. The larvae, once hatched, burrow in and nourish themselves on the internal organs of the host.
Parasitic wasps (Order Hymenoptera)
Most wasps are parasitic or predaceous on other insects. Many are too small to see. The female adults lay their eggs in or on the bodies of the hosts, which can include aphids, scales, thrips, caterpillars and insect eggs. When the eggs hatch, the larvae feed on the host and emerge from the carcass as an adult, leaving only the empty insect husk or “mummy.”
We gardeners are gifted with a bounty of nature’s beneficials. We should never underestimate their miraculous existence or the work they do for us in our gardens. If an insect is doing no observable damage and you can’t identify it, give it the benefit of the doubt and let it be. Who knows? It might be a friend. Practice the wisdom of Antoine de Saint-Exupéry’s “Little Prince”: “I must endure the presence of a few caterpillars if I wish to become acquainted with the butterflies.”
Perwich is a member of the San Diego Rose Society, a Consulting Rosarian and a Master Gardener with UC Cooperative Extension.