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Beneficial Insects

Many insects cause damage to garden plants but others can do a very effective job of keeping problem insects in check without the use of pesticides. Therefore, it behoves the responsible gardener to learn to identify beneficial insects and encourage them whenever possible. Here is a selection of some common beneficial insects.
Images: Click on image to enlarge or on underlined captions for more information.

Predatory beetle (Coleoptera) on tulip tree (Liriodendron) leaf
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Margined leatherwing beetle (Coleoptera), also called goldenrod soldier beetle, Chauliognathus, on garlic chives (Allium). Adults feed on nectar and pollen; larvae possibly feed on corn earworms and root maggots
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Webbing like this indicates that a spider (Aranae) is nearby; all spiders are beneficial predators
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Spiders (Aranae) are beneficial predators. Here, only the web is visible on a spruce (Picea), but the spider's probable location is obvious.
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Swallowtail on zinnia
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Two egg cases of a Chinese praying mantis (Dictyoptera)
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Yellow lady beetle eggs (Coleoptera) on tomato (Lycopersicon)
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Yellow lady beetle eggs (Coleoptera) with their future victim, an aphid (Hemiptera), on a tomato leaf (Lycopersicon)
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Close-up of yellow lady beetle eggs (Coleoptera) with their future victim, an aphid (Hemiptera), on a tomato leaf (Lycopersicon)
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Swarm of honeybees (Hymenoptera) on crabapple tree
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Swarm of honeybees (Hymenoptera) on crabapple tree
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Underside of minute black scavenger fly (Diptera)
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Minute black scavenger fly (Diptera)
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Minute black scavenger fly (Diptera); these insects may congregate in large numbers on compost piles but are benign and simply part of the decay process
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Wheel bug, Arilus cristatus, is one of the largest of the assassin bugs (Hemiptera)
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A wheel bug, Arilus cristatus, is so called because of the semi-circular cog on its back that resembles a cogged wheel. Like other assassin bugs (Hemiptera) they eat other insects and their eggs
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Wheel bugs (Hemiptera), Arilus cristatus, are especially fond of caterpillars which they stab with their sharp beak and suck out the body fluids
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Praying mantis (Dictyoptera) checking for pests on a hosta (Hosta)
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Look closely! Death is lurking on the inner stems of this aster in the form of a camouflaged praying mantis (Dictyoptera)
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Antlions (Neuoptera) are the larvae of an insect related to lacewings. Like lacewing larvae, they are beneficial predators.
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Antlions (Neuroptera) are voracious predators that lie in wait for their victims, usually under loose soil, although sometimes in trees.
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Some antlions called doodlebugs (Neuoroptera) dig a conical pit in loose sand to trap prey. Note, the enornous mandibles on this specimen used to eat ants and other insects.
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Monarch butterflies (Lepidoptera) gathering on a dogwood (Cornus)
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Not all flies (Dipera) are pests; many are parasites and many are part of the natural decay process
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Stag beetle (Coleoptera). The adults are benign; the larvae (grubs) feed on decayed wood
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The white cocoons visible on the back of this tobacco hornworm (Lepidoptera) are braconid wasps (Hymenoptera) that have eaten the hornworm alive
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The white cocoons on the back of this tobacco hornworm (Lepidoptera) are braconid wasps (Hymenoptera) that have eaten the hornworm alive
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Dragonfly (Odonata) on waterlily (Nymphaea)
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Tobacco hornworm (Lepidoptera) on tomato (Lycopersicon) with parasitic braconid wasps (Hymenoptera) in the white cocoons on its back
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If you see a mass of eggs like this, leave it where it is. Wheel bugs (Hemiptera), Arilus cristatus, are beneficial insects that are especially fond of caterpillars
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Wheel bug eggs (Hemiptera), Arilus cristatus, on a ash twig (Fraxinus)
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Close-up of wheel bug eggs (Hemiptera), Arilus cristatus; note, barrel-shape of the eggs typical of true bugs
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Wheel bug eggs (Hemiptera), Arilus cristatus
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Chinese praying mantis (Dictyoptera)
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Chinese praying mantis (Dictyoptera) eating its prey
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Close-up of Chinese praying mantis (Dictyoptera) devouring its prey
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This cicada killer wasp (Hymenoptera), itself a beneficial insect, was parasitized by these fly larvae or maggots (Diptera)
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The pupa of a parasitic fly (Diptera) that came out of a cicada killer wasp (Hymenoptera) while it was still alive
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Cicada killer wasp (Hymenoptera)
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Underside of cicada killer wasp (Hymenoptera)
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Some lacewing larvae (Neuroptera) stick the bodies of the victims to their backs, making them look like moving piles of debris.
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European paper wasp (Hymenoptera)--Polistes dominulus-- often mistaken for a yellow jacket, but note unique orange antennae. Adults feed on nectar; larvae are fed caterpillars and other insects.
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Predatory beetle (Coleoptera) on tulip tree (Liriodendron) leaf
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Even indoors, spiders (Araneae) can be beneficial; this one has caught difficult-to-control whiteflies (Hemiptera) on crown of thorns (Euphorbia milii)
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Even indoors, spiders (Araneae) can be beneficial; this one has caught difficult-to-control whiteflies (Hemiptera) on crown of thorns (Euphorbia milii)
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Predatory beetle (Coleoptera) on tulip tree (Liriodendron) leaf
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Close-up of green lacewing larva (Neuroptera) eating euonymus scale (Hemiptera) on euonymus (Euonymus)
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Green lacewing larva (Neuroptera)
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Green lacewing egg (Neuroptera) on stalk over woolly apple aphids (Hemiptera) on hawthorn (Crataegus)
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Close-up of a ladybird beetle larva (Coleoptera)--also called a ladybug--on birch (Betula)
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Close-up of the head of ladybird beetle larva (Coleoptera)--also called a ladybug--on birch (Betula)
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Close-up of the head and thorax of a praying mantis (Dictyoptera)
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Egg case, with ruler for scale, of a Carolina mantis (Dictyoptera)
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Side view of the egg case of a Carolina mantis (Dictyoptera)
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Top view of egg case of a Carolina mantis (Dictyoptera)
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Braconid wasps (Hymenoptera) are an important natural control of hornworms on tomato (Lycopersicon); note white eggs along back of caterpillar (Lepidoptera)
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Nymph assassin bug (Hemiptera )
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Nymphal stage of a dragonfly (Odonata)
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Rosie, a praying mantis (Dictyoptera),spent the entire summer in a hanging basket of kalanchoe (Kalanchoe and moss rose (Portulaca grandiflora); long enough to be named
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Rosie, a praying mantis (Dictyoptera), spent the entire summer in a hanging basket of kalanchoe (Kalanchoe and moss rose (Portulaca grandiflora); long enough to be named
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The cast skin of Rosie, the praying mantis (Dictyoptera)
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Rosie, the praying mantis (Dictyoptera), praying for another victim
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Egg mass of a Chinese mantis (Dictyoptera)
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Egg mass of a Chinese mantis (Dictyoptera)
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Egg mass of a Chinese mantis (Dictyoptera)
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Egg mass of a Chinese mantis (Dictyoptera)
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Spiders (Araneae), like this garden master, are beneficial predators in the garden
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Most solitary hunting wasps (Hymenoptera), like the mud dauber, are considered beneficial insects
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Green lacewing larva (Neuroptera), some of which are called aphid lions, not only eat aphids, but also eat other soft-bodied pests
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Close-up of green lacewing larva (Neuroptera)
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Cicada killer wasps (Hymenoptera) are considered beneficial insects because they prey on dog-day cicadas
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Dragonfly (Odonata) on (Ratibida pinnata)
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This common house centipede (Chiropoda) is not an insect--it has 15 pairs of legs--but it can be considered beneficial as its primary food is small household insects
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Potter wasps (Hymenoptera) rarely sting and are predators of caterpillars and beetle larvae, which they catch and then paralyze for their own larvae to feed on.
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Dragonfly (Odonata) on coleus (Solenostemon)
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On the right is a cicada killer wasp (Hymenoptera); on the left is its prey, a cicada (Hemiptera)
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Praying mantis (Dictyoptera)
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Assassin bug (Hemiptera )
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Assassin bug (Hemiptera ) on pine (Pinus)
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Close-up of green lacewing adult (Neuroptera)
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© Missouri Botanical Garden, 2001-2009