Beneficial insects

by M. Arjoca,

Beneficial insectsThe insects are one of the most diverse animal groups on planet, living in almost every environment. There are over a million species described and there are many more unknown.

In the garden live a lot of insects, many of them eating our precious plants. Nevertheless not every insect is bad. There are also many beneficials. They help the gardeners pollinating the flowers and assisting on pest control.

The flowers pollination is done beside the wind, birds, animals, water, with the help of insects. The bees, butterflies, wasps, flies, ants, bugs etc. are the most important and common pollinators. Their importance is so big that there are commercial suppliers who sell different insects especially for greenhouse plants. Also the farmers of hazel, apple, coffee trees and other trees bring hives every spring to their orchards. In the same way proceed the farmers of tomatoes, cucumbers, pumpkins, strawberries and other vegetables and fruits.

Organic gardeners rely on predatory insects for pest control. The predatory insects feed themselves with other insects (with those who eat our plants) and/or with their eggs and larvae. For example, the larvae from some species of hoverflies eat aphids, leafhoppers, thrips and other pests.

Some good insects called parasitic (like Ichneumon wasps), lay their eggs inside the body of other insects or caterpillars so when the eggs hatch, the larvae have a secure source of fresh food.

The idea is not to eliminate for good the pest insects but to maintain a balance between them and the good ones.

Some insects are pests in larva stage, but very useful in the adult stage. For example, the larvae of tomato fruitworm (Helicoverpa zea ) are real pests, but the adults are important pollinators.

Many times the predatory insects eat not only bad insects, but also our allies, the good ones. The parasitic wasps eat not only caterpillars but also ladybugs who can help us eliminate the aphids. Dragonflies do the same thing. Praying mantis (Mantis religiosa, or Mantodea) is a perfect hunter and many gardeners want it in their garden. Unfortunately it can not distinct between the pests and our helpers.

flowers from Asteraceae familyGenerally the insects feed themselves not only with other insects but also with pollen and nectar, many of them even if they are carnivorous in the larva stage, in the adult stage feed themselves with pollen. That’s why having in garden flowers rich in pollen and nectar, which bloom in different seasons, is a good way to attract beneficial insects.

Some gardeners try to attract them growing certain flowers or companion plants. Generally beneficial insects are attracted by flowers from aster family (Asteraceae) and umbellifers family (Umbelliferae).

To Asteraceae family belong: the daisies, asters, chrysanthemums, sunflowers, dahlias, calendulas, tagetes, zinnias, strawflowers, camomile, tarragon, lettuce, cornflower, chicory, dandelion, gerbera, thistle, wormwood etc.

plants with umbel flowers Umbellifers have their flowers arranged in a form of umbels and attract especially parasitic wasps and predatory flies. To their family belong: the dill, carrot, parsnip, parsley, lovage, celery, coriander, fennel, anise, angelica, chervil, caraway etc. Beside Umbellifers there are many plants from other families which have umbel flowers. The insects are attracted by small flowers grouped together.

But every gardener can notice what kind of insects appear in his garden and what plants attract them mostly.

Here are some beneficial insects, their action and the plants which attract them.

Beneficial insects

Eat / Action
Attractive plants


(Apis mellifera)

Sunflower, echinacea, yarrow, onions, chives, borage, cornflower, foxglove, lavender, bee balm, nasturtium, sage, thyme, verbena and many others


(Coccinellidae )

Aphids, different pests butterflies, mites, scales, mealybugs, fungus gnats
Alyssum, carrot, fennel, yarrow, bean, pea, alfalfa, daisies, buckwheat, cosmos, dandelion, calendula, chives, wild mustard



Mosquitoes, aphids, bugs, flies
Water sources, water plants, cosmos, fennel, caraway

Soldier beetle


Grasshopper eggs, aphids, mites, butterflies larvae, leaf miners, cucumber beetles, Mexican bean beetles, cabbage worms, eggplants bugs, Colorado potato beetle, asparagus beetle
Hortensia, milkweeds, echinacea, rudbeckia, generally Asteraceae



Aphids, whiteflies, mites, some caterpillars, mealybugs, thrips, scales, fungus gnats
Sunflower, coriander, cosmos, fennel, yarrow, daisies, caraway, dandelion, angelica

Parasitic wasps


Aphids, butterflies larvae, flies, bugs
Asters and umbellifers, crocuses

Parasitic wasps



Caterpillars, whiteflies, codling moth (attack the pears, apples, walnuts), Ostrinia, tomato fruitworm (the larvae attack the tomatoes, corn, cotton)
Parsley, dill, coriander, fennel, caraway, cosmos, yarrow, lemon balm, tagetes, thyme, zinnia, daisies, crocuses

Ichneumon wasps



Lice, bugs, flies, wasps, bees, ants, eggs and larvae of butterflies and other insects, whiteflies
Lavender, dill, alyssum, candytuft, lemon balm, mint, camomile, yarrow, daisies, caraway, coriander, buckwheat, fennel, zinnia, parsley, sedum, tagetes, thyme, statice, crocuses



Aphids, thrips, mealybugs, caterpillars, leafhoppers, scales
Lavender, dill, alyssum, candytuft, lemon balm, mint, camomile, yarrow, daisies, caraway, coriander, buckwheat, fennel, zinnia, morning glory, parsley, tagetes, sedum, thyme, statice

Tachina flies


Caterpillars, flies and bug larvae, bugs, grasshoppers
Parsley, thyme, mint, cosmos, daisies, lemon balm, buckwheat

Minute pirate bug


Spider mites, thrips, aphids, whiteflies, fungus gnats
Cosmos, alyssum, fennel, carrot, sunflower

Damsel bug


Cabbage worms, aphids, Lygus bugs
Bean, pea, alfalfa, soy

Big-eyed bug


Grasshoppers, mites, whiteflies, cabbage loopers, aphids, insect eggs
Mint, fennel, cosmos, tagetes, caraway, alfalfa

Spider on a pepper leafSpider                  


Different insects
Flowers, leaves, branches, twigs, grass etc.