Posts Tagged ‘pollinator conservation’

Bring Back the Native Pollinators! We Need them More than Ever

May 20, 2015
A long-horned bee on sunflower © Beatriz Moisset

A long-horned bee on sunflower
© Beatriz Moisset

Excerpt from the USDA document prepared by the Division of Bee Culture in 1942: “The Dependence of Agriculture on the Beekeeping Industry—a Review.”

Wherever a proper balance exists between plants and pollinating insects, both flourish. Agricultural development, however, has seriously interfered with this balance. It has demanded the growing of certain plants in enormous acreages and has unwittingly destroyed native pollinating insects as well as their nesting places. As a result the burden of pollination has been increased to such an extent that wild bees are no longer adequate or dependable. . . In many places the depletion of wild pollinators is so acute that honeybees have to be brought in especially for pollination, and so in practically all agricultural areas honeybees are now the most numerous of the flower-visiting insects.

Read the full article in Native Plants and Wildlife Gardens 2014

Pumpkin patch teeming with bumble bees © Beatriz Moisset

Pumpkin patch teeming with bumble bees
© Beatriz Moisset

The Milkweed Community

May 13, 2015
Monarch butterfly on common milkweed © Beatriz Moisset

Monarch butterfly on common milkweed
© Beatriz Moisset

The monarch season is coming, and many gardeners throughout the country are getting ready to welcome the arriving butterflies with milkweeds lovingly cultivated in their gardens. They also brace themselves to battle whatever ills may affect the caterpillars. Milkweed bugs and milkweed beetles are seen with hostility. The “dreaded” tachinid flies, and “hated” stink bugs infuriate gardeners even more. Aphids are not welcome. Lady beetles and lacewings generate mixed feelings because they feed on aphids but they are not loath to snack on some monarch eggs or small caterpillars.

Spotted Lady Beetle larva (Coleomegilla maculata) © Beatriz Moisset

Spotted Lady Beetle larva (Coleomegilla maculata)
© Beatriz Moisset

It is important to take a look at entire ecosystems, not just single species as Carole says in “Saving the Monarch Butterfly

“The Monarch Butterfly is in deep trouble, and many passionate organizations have been created to save this single species. But a focus on protecting habitat instead of concentrating on a single species will provide lasting benefits for all species of wildlife and the native plant communities that support them, a far more worthy effort to many environmentalists and wildlife gardeners.”

So, let us take a quick look at some members of the milkweed community. Despite the formidable defenses these plants have, many species have coevolved with them and can use them as food. They incorporate the milkweed toxins and use them to deter their enemies. In turn, many predators have also coevolved and can eat the milkweed eaters. An entire food chain has developed this way.

Large milkweed bug, Oncopeltus fasciatus on common milkweed © Beatriz Moisset

Large milkweed bug, Oncopeltus fasciatus on common milkweed
© Beatriz Moisset

Milkweed longhorn beetles on common milkweed © Beatriz Moisset

Milkweed longhorn beetles on common milkweed
© Beatriz Moisset

Most monarch lovers are familiar with the brightly colored milkweed bugs and milkweed longhorn beetles. Bear in mind that these insects are represented by a fairly large number of species. That is, there are more than just one milkweed bug and one milkweed beetle. A few other beetles also feed on milkweeds, and several moths also do so, among them the tussock moth and the delicate cycnia.

Tussock moth caterpillar © Beatriz Moisset

Tussock moth caterpillar
© Beatriz Moisset

Sooner or later, those who raise monarch caterpillars are bound to meet two insects which will make them unhappy; one is a predator, the spined soldier bug, the other a parasite, the tachinid fly, Lespesia.

The spined soldier bug, Podisus maculiventris, is a good hunter of caterpillars and beetle grubs. It has a sharp beak with which it impales its victims. It injects some saliva which turns the inside of the prey into a smoothie and so it proceeds to drink this nutritious cocktail. The sight of a shriveled monarch caterpillar hanging from the beak of a stink bug causes great distress to the gardener.

Predatory stink bug, Podisus maculiventris on goldenrod. © Beatriz Moisset

Predatory stink bug, Podisus maculiventris on goldenrod.
© Beatriz Moisset

Podisus maculiventris juvenile (nymph) feeding on dogbane caterpillar © Beatriz Moisset

Podisus maculiventris juvenile (nymph) feeding on dogbane caterpillar
© Beatriz Moisset

The tachinid fly mentioned above goes by the name of Lespesia. It lays its eggs on caterpillars of a large number of species. The tiny fly larva digs inside and proceeds to eat its victim until it reaches full size. Then it comes out of the dying caterpillar and dribbles a sticky trail until it drops to the ground. Not a pretty sight.

Tachinid fly, Lespesia © Stephen Luk

Tachinid fly, Lespesia
© Stephen Luk

Tachind fly, Lespesia, Puparium and parasitized tent caterpillar's cocoon © Stephen Luk

Lespesia puparium and parasitized tent caterpillar’s cocoon
© Stephen Luk

Although these two insects on occasion kill some monarchs, we should not hate them. Actually, their diet is so diverse that it includes a number of pests. They are both used as pest controls for this reason and even sold for this purpose. Podisus is known to eat Mexican bean beetles, European corn borers, diamondback moths, corn earworms, beet armyworms, fall armyworms, cabbage loopers, imported cabbage worms, Colorado potato beetles, and velvetbean caterpillars. The tachinid fly is reported to feed on tent caterpillars, armyworms, cutworms and corn earworms.

Nature is far more complicated than it appears at first sight. It may seem paradoxical, but the spined soldier beetle and the Lespesia fly are indirectly the friends of monarchs, because they help cut down on pesticides. Moreover, we must remember that they have coexisted with monarchs for eons without driving them to extinction. The same can be said about the milkweed herbivores –beetles, bugs and moths. They haven’t driven milkweeds to extinction and they are not likely to do so. We are the ones that pose a threat to milkweeds and to monarch butterflies with our pesticides, habitat destruction and introduction of invasive species.

Let saving the pretty butterfly be the portal to saving the entire community, all the creatures that creep and crawl, the ones that jump or fly and even the ones that kill or get killed. Let us embrace the web of life in its totality, with all its beauty and ugliness.

Delicate cycnia © Beatriz Moisset

Delicate cycnia
© Beatriz Moisset

Additional readings
You may find this Flickr album interesting: Milkweed Visitors
More members of the milkweed community
The monarch butterfly as part of the food web: Monarchs and their Enemies

This article first appeared in Native Plants and Wildlife Gardens

You can help pollinators in your own garden

March 9, 2011

Here are some of the things you can do to help pollinators in your garden:

Plant a pollinator garden. Turn some of your lawn into a wildflower meadow. One major objection of gardeners, the fear of stings, doesn’t need to be a serious concern. Most native bees are quite different in this respect from honeybees and hornets; they hardly ever sting and if they do, it is very mild. In fact there are some, such as the Andrenids, that are incapable of doing so. Their stingers are too small to penetrate human skin.

Avoid pesticides or if you absolutely need to use them, inform yourself carefully about the specific pesticides that kill only the target species, rather than decimating many others unintentionally. Furthermore, avoiding pesticides may not be as bad as it sounds since nature has its own checks and balances and manages to keep most pests under control without resorting to pesticides. There are some cases in which use of pesticides backfires by destroying these checks and balances. Avoid herbicides also; they can be bad for pollinators. They either deprive them of food or poison them.

Plant native flowers, that is flowers that grow locally, not just native to the United States; these are best for pollinators. Some bees may be able to adapt to non-native plants, such as many fruit trees or some of the less fancy cultivars. But native pollinators and native plants have become mutually adapted through millions of years, so they make the perfect match in most cases.

Grow a variety of flowers that bloom through the seasons. This is good for native bees; fortunately this is also what most gardeners aspire to have in their gardens. However highly selected cultivars or those with doubled-flowers don’t take care of the needs of pollinators. In general they have lost all the cues that pollinators need, such as scent. In some cases, they have also lost the pollen or nectar and so they don’t provide any food to bees.

Plant the kind of lawn that provides habitat beneficial to bees. A perfectly manicured, pesticide saturated lawn is a desert to wildlife, including pollinators. Reducing the size of the lawn would benefit native pollinators. But it is also possible to have a lawn that is good for bees while being esthetically pleasing. As mentioned before, stay away from pesticides and herbicides as much as possible. Second, allow some small wildflowers; the look of your lawn may change as a result but it will continue to serve its purpose. Clover is great food for native bees; it also fixes nitrogen cutting down the need for fertilizers. Other small plants that benefit bees are ground speedwells (Veronica), wood sorrel (Oxalis acetosella), smartweeds or knotweeds (Polygonum), wild strawberries (Fragaria, several species), etc. Rather than calling them weeds we should call them grass companions or pollinator food.

Provide housing for bees. A simple bare spot here and there (no mulch or grass, just bare soil) may be enough for a few hard-working soil nesters. A sand pile may be even better. It bears repeating: There is no real need to worry about stings from solitary bees.

Dead logs or snags can supply housing for bees. You probably can’t have a dead tree on your property, but it is possible to keep a stump or a standing log and use it as an attractive planter; perhaps it will in turn provide housing for some little bees. Drilling holes on an old post or even a tree trunk would also make good nesting sites. They should be 3/32” to 3/8” in diameter and at least 4” deep.

Or you can make your own bee houses. It is possible and relatively easy to build one by following instructions posted in several websites. Or you can buy one; some resources listed below. I have discovered that watching the comings and goings of those busy mother bees can be as much fun as observing a bird house. Once again, stings don’t seem to be a real problem; I have had my face right in front of their houses and have even let them climb on my finger without any consequences.

Hollow tubes, just about the size of drinking straws, can also be used as bee nests. Some of the suppliers listed sell them. You can also tie up a bunch of hollow twigs, such as elderberry, or paper drinking straws (plastic ones are no good) together or pack them into a container such as a small milk or cream carton and place them horizontally. They should be closed at one end with the open end facing south or southeast. If you have trouble figuring out where the south is, step outside sometime between 10 AM and 1 PM and face the sun. That is how you want to place the nests. (See links below for instructions).

You can let some of your ornamental grasses stay all winter; they can be quite handsome and add variety to your winter landscape while providing nesting to your friendly native bees.

Helping the native bees would benefit us because of their invaluable services to the environment and to our gardens.

Resources

Ross, Edward S. (2003) Pollinator Conservation Handbook. The Xerces Society and The Bee Works. Portland, Oregon ISBN 0-9744475-0-1. (Bee gardens, bee houses, etc.)
The Xerces Society Guide (2011). Attracting Native Pollinators. Storey Publishing. ISBN 978-1-60342-695-4 (Everything you want to know about pollinators and their conservation)

Urban Bee Gardens. Berkeley University
Nests for Native Bees. The Xerces Society
Bee houses. National Wildlife Federation. (How to build a bee house)

Sellers of bee houses
Knox Cellars.
Mason bee homes.

Native bees, conservation

March 7, 2011

In recent years the general public has become aware that honeybees are in serious trouble. What most people don’t know is that not just honeybees, but also some native bees and other pollinators, seem to be suffering difficulties for a number of reasons. Unfortunately we know so little about this huge number of species of bees that it is hard to assess fully the situation and the causes. Buchmann and Nabhan called attention to this problem as early as 1996 in their book, The Forgotten Pollinators. There, they discussed the need to learn more about native pollinators and to take steps toward protecting them.

It may seem strange to most but honeybees may be contributing to the extinction of some native bees. Honeybees can out-compete many of them. We can only guess what the impact of the arrival of honeybees has been on the populations of native bees starting with the early settlers.

It appears that, as in many other cases, habitat reduction and fragmentation affect the populations of native bees. Pesticides are without doubt bad for many species of native bees. This became dramatically apparent in New Brunswick, Canada years ago when the blueberry crop was disastrously low, despite the fact that the plants appeared healthy. Finally, it was found that the battle to control the spruce worm in the nearby forests had wiped out the native bees. Blueberry farmers started a litigation that went all the way to the Supreme Court of Canada until they succeeded at placing restrictions on the use of pesticides. It took a number of years before the populations of bees were restored and the blueberry crops became plentiful again.

The situation of native bees in the United States has caused enough concern that the National Research Council of the National Academy of Sciences issued a report titled “Status of Pollinators in North America” in October, 2006. The document presents conclusive evidence of downward long-term trends of the populations of some native pollinators, including solitary bees and especially some bumblebee species. Additional data on trends and their causes keeps coming in recent publications.

Some of the recommendations of the Research Council are the creation of economic incentives for the study of bee populations through a system of long-term monitoring and for the development of practices promoting pollinator preservation. Another recommendation is to encourage land managers and owners, including farmers and homeowners to develop “pollinator-friendly” practices, many of which require only a small increase in expenditures.

A number of organizations are creating pollinator gardens with the types of plants and habitats that benefit bees and other pollinators. The Xerces society supplies information to those who want to start one.

In Canada the citizens of Guelph in Ontario, Canada, have gone a step further creating the world’s first Pollinator Park at the Eastview landfill site. In part they were inspired by the experience with the blueberry pollination disaster. They are turning an ordinary landfill, about one hundred acres, into an oasis for bees and other pollinators with the right plantings and proper habitat for nesting.

Resources
Status of Pollinators in North America . The National Academies.
North American Pollinator Protection Campaign
How to Protect and Enhance Habitat for Native Bees.