Attracting beneficial insects

ladybugEverything eats something, and in turn is fed upon by something else. We can use this fundamental relationship to help control pest populations in the garden by attracting beneficial insects. There are four major types of beneficial insects; predatory, parasitic, pollinators and decomposers. All play an important role in a healthy landscape, but this information will focus on the predators and parasites, as they will directly control detrimental pests in the
garden such as aphids, caterpillars, mites, mealy bugs and others.

How to attract beneficial insects

Stop using any chemical control

Using chemical control, organic or inorganic, can harm beneficial insects. While you may think you are targeting the ‘bad guys’, residues and drift from the application of various products can harm a wide range of insect life (including the ‘good guys’). Taking advantage of beneficial insects requires that a balance be achieved between predator and prey, and allowing a healthy balance of both to develop is crucial to success.

Provide water

Providing a water source will greatly increase the diversity of insects in your garden, and likely ring in other insect eaters like toads, frogs and birds. Water sources for insects do not need to be large or showy. A shallow dish with wetted stones is often enough to supply insects with the water they need. If space allows, a small pond will make possible the development of dragonfly larva and attract breeding toads, both of which are ravenous feeders on various insect pests.

Provide shelter

insect shelterThe highly manicured garden provides very little shelter for beneficial insects compared to their natural habitat. To gain clues as to where these insects like to live, just think of a non-tended space, such as a hedgerow or woodlot. By simulating some of these conditions in the garden, the appropriate homes can be created for beneficial insects both during the summer as well as during the winter season. Mulches of bark and leaves provide ground dwelling insects with hiding places, while having layers of canopy or upper level growth provide roosting and egg laying sites for many flying species. Rolling newspaper into narrow tubes or cutting bamboo into varying lengths and clustering them together under a small roof-like structure can provide a great home for a wide variety of insect life. A small pile of branches is also of great benefit in providing overwintering habitat. Try to leave some areas of open bare soil for ground nesting bees and wasps. Remember, having a diverse habitat will attract the most number of species, and the more diverse the habitat the more stable it is.

Provide food

Insects tend to have different feeding requirements during the various stages of their development, and though beneficial insects to feed heavily on pest insects, there may be certain points in their life cycle when their diet consists mainly of nectar and/or pollen. By having a wide diversity of plant material you can increase your chances of providing the right food at the right time for your beneficial insects. Plants in the carrot family (Apiaceae) and mustard family (Brassicaceae) are particularly good for providing pollen and nectar to beneficial insects. It is important to ensure that you are planning your garden to privide bloom (nectar/pollen) throughout the year, from spring until fall.

Beneficial insects and their food preferences

 

Insect

Preferred plants

Insects controlled

Lacewing Yarrow, Achillea spp.
Dill, Anetheum graveolens
Queen Anne’s Lace, Caucus carota
Sunflower, Helianthus spp.
Tansy, Tanacetum vulgare
Dandelion, Taraxacum officinale
Mites, aphids, mealybugs, soft scale and a wide variety of small insects and insect eggs. The larva are particularly good at controlling aphids.
Ladybird / Ladybug Yarrow, Achillea spp. 
Basket of Gold, Alyssum saxatilis 
Dill, Anethum graveolens
Fennel, Foeniculum vulgare 
Sunflower, Helianthus spp. 
Cineuqfoil, Potentilla spp. 
Butterfly Weed, Asclepias tuberose
Dandelion, Taraxacum officinale
Aphids are the primary food source, though ladybird beetles will consume other small soft bodied pests as well. The larva are orange and black, and consume huge numbers of aphids per day.
Hoverflies Yarrow, Achillea spp. 
Basket of Gold, Alyssum saxatilis 
Aster, Aster spp.
Parsley, Petroselinum cripsum 
Fennel, Foeniculum vulgare
Lavender, Lavandula angustifolia 
Cinquefoil, Potentilla spp.
Adults look somewhat like small bees, though they can not sting. The larva look like small green/white caterpillars and feed on aphids, thrips, mealybugs and many other small insect pests.
Parasitic mini-wasps Yarrow, Achillea spp. 
Dill, Anethum graveolens 
Fennel, Foeniculum vulgare 
Parsley, Pertroselinum crispum 
Cinquefoil, Potentilla spp. 
Stonecrop / Sedum, Sedum spp. 
Thyme, Thymus spp.
These tiny wasps do not sting, but rather their stinger has been adapted to allow females to lay eggs in the bodies of insect pests. The eggs hatch and the young parasitize the host. Most parasitize caterpillars and beetle larvae.
 Tachinid flies Golden Marguerite, Anthemis tinctoria 
Lemon Balm, Melissa officinalis 
Parsley, Petroselinum crispum 
Thyme, Thymus spp.
Parasitize a wide variety of caterpillars, stink bugs, squash bug nymphs and beetle larvae. The adult is a 1/3” -1/2” long black fly.
Minute pirate bugs /
damsel bugs /
big eyed bugs
Fennel, Foeniculum vulgare
Goldenrod, Solidago spp.
Marigold, Tagetes spp.
Alfalfa, Medicago sativa
These small insects eat a wide variety of pests including leaf hoppers, plant bugs, scale, spider mites, aphids, thrips and whiteflies.