Beautiful Native Plants

Blog HOME ***Our team of bloggers writes about all aspects of ecosystem gardening, from native plants to pollinators and wildlife.***

Tuesday, July 12, 2016

Pollinator Gardens do Double Duty

Syrphid flies. Pollinators and biological controls. Their larvae feed on aphids
© Beatriz Moisset

More gardeners are learning about pollinators and creating habitat for them. It warms my heart when I see them selecting plants beneficial to pollinators, converting portions of the lawn into flower plots, cutting down on pesticides, and creating the right conditions for pollinators’ nests. Many gardeners are learning to be grateful to pollinators for their services. Some are familiarizing themselves with the most common ones. This is a healthy trend.

Syrphid fly larva devouring aphids
© Beatriz Moisset
An additional advantage of pollinator gardens is that they serve another useful function. Many other beneficial insects depend on pollinator gardens and, in turn, gardens and farms profit from their presence. I am referring to predators and parasites of plant-eating insects. Such beneficial insects have earned the name of biological controls, or biocontrols for short. Many biocontrols need nectar, or nectar and pollen, during part of their life cycle. Some of them prefer to eat insects but can survive on nectar and pollen in the absence of their prey. Thus they are ready to spring to action when the unwanted pest arrives. Gardens lacking on floral resources are not as well protected against pests.

Tachinid fly, Trichopoda pennipes. Its larvae feed on insects
© Beatriz Moisset
The extra bonus of growing a pollinator garden became apparent in studies done by Cornell University. Apple growers could cut down pesticide treatments from ten to two or three a year when they started growing plants for pollinators.

Robber fly, Laphria thoracica, a formidable hunter of insects
© Beatriz Moisset
It is a great thing that the needs of pollinators and those of many biocontrols overlap. Syrphid flies illustrate this point. The adults are bee-like and hover over flowers, earning them their common names, flower flies or hover flies. They feed on nectar and pollen and manage to do some pollination. Their larvae are little green maggots that feed voraciously on aphids. They frequently escape notice. I have learned to check aphid colonies and frequently I find some of these maggots doing what they do best, getting rid of aphids.

An ichneumonid parasitic wasp
Its impressive appendix is an ovipositor (egg laying organ), not a stinger
So there is nothing to fear from this wasp
© Beatriz Moisset
One of the solitary predatory wasps, potter wasp (Eumeninae)
hunting a caterpillar hiding on the flower head
© Beatriz Moisset
Here are a few other examples of biocontrols that prosper in pollinator gardens: Tachinid flies, some of which are hairy, robust and rather ugly, while others are elegant and colorful. All lay their eggs on or in other insects and help control many pests, even gypsy moths and Japanese beetles. Robber flies are fast fliers and skillful at pouncing on unsuspecting victims. Wasps are great garden helpers, both the parasitic ones, which lay eggs on other insects, and the predatory ones, which catch prey to feed their babies. The adults feed primarily on nectar and pollen. It is good to remember that parasitic wasps don’t sting and that most predatory ones are not inclined to do so. In most cases there is no need to fear these wonderful biocontrols. Assassin bugs have front legs that resemble those of praying mantises and, like them, use them to grasp their prey with a swift movement. Not all stink bugs are plant pests; the predatory ones feed on the pests themselves. The merits of lady beetles as eaters of aphids and other soft bodied insects hardly need mentioning. Both larvae and adults feed on these pests. The adults are also fond of nectar and pollen. Other beetles worth mentioning are the soldier beetles, so called because their colors and pattern resemble those of old army uniforms. They are frequently seen visiting goldenrods.

Assassin bug, Zelus luridus
© Beatriz Moisset
Among the plants that feed both pollinators and biocontrols are many Asteraceae, such as coneflowers, coreopsis, yarrow, and goldenrods. Other families include Apiaceae, the carrot family, Lamiaceae, the mint family, Euphorbiaceae, the spurge family, and Fabaceae, the pea family. The best information on planting for pollinators by region is provided by the Pollinator Partnership. You can also find some information in Attracting Beneficial Insects with Native Plants.

Soldier beetles, Chauliognathus
© Beatriz Moisset
In summary, your pollinator garden does double duty, helping pollinators and also biological controls. Perhaps we could say that it does triple duty, as many of the flowers are beautiful and we get to enjoy them too. Happy plantings!

Polished lady beetle, Cycloneda munda
© Beatriz Moisset

© 2015, Beatriz Moisset. First published in Native Plants and Wildlife Gardens. 4/7/15