Sunday, February 22, 2015

The Solution to Fewer Native Plants is Fewer Native Plants?

Recently someone on a message board was advocating that we respond to the decline in native plants by planting more non-native plants. The issue in question was having fewer nectar sources for butterflies due to habitat destruction and development of wild lands into subdivisions, shopping areas and commercial real estate.

This is not the first time that I've seen someone advocate using non-native plants specifically because there are fewer native nectar sources than before. It implies a “we can make nature better” mindset.

This approach demonstrates a lack of understanding in regards to insect life cycle, a lack that was all the more startling given that it was being demonstrated by someone that was arguing on behalf of the monarch butterfly. The monarch butterfly is THE “poster butterfly” for the larval-host plant relationship. Monarchs need milkweed (Asclepias spp.) to lay their eggs on, right? Without milkweed plants, monarch butterflies cannot survive and the last two years have dramatically demonstrated that.

One cannot focus only on nectar plants - nectar is only used by the adults. The needs of the larvae are completely different from the adults. By advocating that non-native plants be used for nectar instead of the nectar-producing natives that disappeared, this person is saying that some butterflies and moths are more worthy than others.

This wingstem (Verbesina alternifolia) supports bees, provides nectar, and  is a host plant

You see, the rest of the native Lepidoptera (butterflies and moths) in North America have similar relationships with their own host plants just like monarchs and milkweed and they need those plants to be available as well. Goldenrod (Solidago spp.) is a top native late summer nectar plant and host to well over 100 different species of butterflies and moths. Here is a short list of some of those special relationships:

  • Silvery Checkerspot (Chlosyne nycteis): host plants include native sunflowers (Helianthus spp.) and common wingstem/crownbeard (Verbesina spp.).
  • Gulf Fritillary (Agraulis vanillae) and Zebra Longwing (Heliconius charithonia vazquezae): both of these lay eggs only on members of the passionvine (Passiflora spp.).
  • Great Spangled Fritillary (Speyeria cybele): host plant is violet genus only (Viola spp.).
  • Zebra Swallowtail (Eurytides marcellus): host plant is only paw paw (Asimina spp.)
  • Great Purple Hairstreak (Atlides halesus): Mistletoe (Phoradendron tomentosum).
  • Henry's Elfin (Callophrys henrici): Redbud (Cercis canadensis).
  • American Lady (Vanessa virginiensis): host plants include cudweed (Gnaphalium) and pussytoes (Antennaria).
  • Cloudless Sulphur (Phoebis sennae) and Sleepy Orange (Abaeis nicippe): both host on what most people might consider weedy legume plants like partridge pea (Chamaecrista fasciculata) and sickle-pod (Senna obtusifolia).
  • Coral Hairstreak (Satyrium titus): Sandhill plum (Prunus angustifolia), and black cherry (Prunus serotina).
  • Spicebush Swallowtail (Papilio troilus): hosts on spicebush (Lindera benzoin), sassafras (Sassafras albidum), tuliptree (Liriodendron tulipifera).
Some Lepidoptera are even named for their host relationships: Hackberry Emperor (Asterocampa celtis) hosts on hackberry (Celtis spp.), the Yucca Giant Skipper (Megathymus yuccae) hosts on Yucca, and Pipevine Swallowtail (Battus philenor) hosts on pipevine (Aristolochia).

This Red Admiral butterfly hosts on stinging nettles

There are some species that have evolved relationships with more than one host such as the Painted Lady (Vanessa cardui) and Common Buckeye (Junonia coenia). Those butterflies have choices, but still they are hosting on native plants, not crape myrtle, not ligustrum, not forsythia or knock-out roses and definitely not on butterfly bush (Buddleja).

While this Zebra Longwing happily nectars on Lantana, there won't be any new ones
unless you have passionvine (Passiflora)

"What about Black Swallowtail butterflies?", you say. They lay their eggs on parsley and fennel, two non-native herbs that are frequently used in "butterfly" gardens. The scientific answer is that both parsley and fennel are in the Apiaceae family which is the same family that contains the native host plants for this butterfly. These same butterflies would naturally host on plants like golden Alexander (Zizia aurea) and any species of Angelica as well as many other native members of the Apiaceae family. Black Swallowtails benefit from this close chemical similarity in plants.

Golden Alexander (Zizia aurea) hosts Black Swallowtail butterflies

For the vast majority of Lepidoptera, however, when you choose to use non-native plants for nectar, you are depriving another Lepidoptera of its host plant. I’m not suggesting this is always a big deal, especially when done in moderation and in consideration of 3 things: quantity, quality and invasive tendencies:

Quantity: having relatively few non-native plants while having mostly native plants is the best approach.
Quality: choosing non-native plants that have abundant nectar and pollen gives you the most bang for the space.
Invasive tendencies: avoiding non-native plants that have invasive tendencies in your area is important.

I will plant a few non-native nectar sources this year, but I'll be mindful of those 3 considerations when I make my choices. We can help some butterflies without hurting others if we make informed choices. 

Nature has already set these relationships between plants and Lepidoptera. We can't change them and we can't make nature "better." We can understand them and we can help to keep them going. That's why we have the big brains.

Sunday, February 15, 2015

Avoid the 'Noids in 2015

This subject is on my mind way too often, but I don’t want to be the only one thinking about it. We all need to be concerned and educated when it comes time to choose our plants this spring.

I’m talking about neonicotinoids (NEO-nik-oh-teh-noids). Neonicotinoids are a type of pesticide that has been widely touted in the last few years as a “safer” type of pesticide against sap-sucking and leaf-chewing insects because it is taken up by the plant through the roots (it is watered in or applied to the seed as a pre-treatment) and doesn’t involve the hazards to humans from treatments like spraying.

These pesticides have been found to not be “safe” for insects that eat or gather pollen and nectar from the treated plants because there are residual amounts of the chemical in the pollen and nectar. That means we don't want these chemicals applied to any plants that require insect pollination (like our fruits and vegetables) or the plants that we use to attract and sustain butterflies.

Neonicotinoids are now considered a likely contributor to problems with bees, problems as serious as killing them outright or at least causing disorientation such that they cannot find their way back to their hives (in the case of European honey bees) or their nests (in the case of native bees). Bees leave the hive or nest to gather pollen and nectar to bring back. Along the way, they will eat some of what they gather for their own nourishment.

Frankly if they cannot find their way back to the hive or nest, they are as good as dead anyway because they are not helping the next generation of bees.  

So what's a conscientious gardener to do? Both plants and seeds need to be considered. One approach is to pre-research everything. A blogger on the West Coast has put together a fabulous collection of information on many of the large growers and seed providers. She contacted them and has published their responses. 

Gardeners who are concerned about purchasing products treated with neonicotinoids have asked for companies to label their plants so that treated plants can be avoided. The Home Depot announced last year that they would require their suppliers to let them know about treatments so that they could label the plants. Bravo! I'm not aware of any other major plant retailer in Georgia that has agreed to provide labeling.

Blueberries treated with neonics

The new labels have now arrived at Home Depot and I thought I'd take a field trip to see how plants and seeds are being labeled there. What is clear is that the labeling on plants is being used to definitely indicate which plants have been treated. Plants that are not labeled can - I assume - be considered as not having been treated by neonics. 

Or the label fell out. Or that pot was missed. You might have to search around to see if other plants (same kind of plant) in the area have tags and the one you picked up was just not labeled. You can see here that the label is just tucked into the pot, and sometimes it is shoved all the way to the soil line.

Here is a picture of the label and it looks like they are probably being applied at the store once the plants are delivered (in other words, it is Home Depot's tag, not the grower's tag). 

I examined all the seed packets at Home Depot and none of them are labeled for neonicotinoids. Several have "non-GMO" labels but that is not the same thing. One package was labeled as "organic" but I am not sure that is a guarantee.

This package happens to be from Ferry-Morse which is not using neonics according to the blog on referenced earlier. It would be more clear if they'd say that.

Non-GMO does not mean no neonics
Does organic mean no neonics?

You also need to consider the pesticide products that are sold for use in the home garden. Look at the labels. Neonicotinoids include chemicals like imidacloprid, clothianidin, thiamethoxam, acetamiprid, and dinotefuran so look for these on the labels. The Xerces Society has a great page about products that are available for home use and which ones should be avoided by consumers.

So if protecting pollinators (bees, butterflies, etc.) is important to you, start reading labels - plant labels and package labels. If you're not sure, ask at the store. Retailers won't realize it is important to us unless we speak up.

Sunday, February 8, 2015

Awaiting the Turn from Brown to Green

American beech (Fagus grandifolia)
As we move into February, warmish and sunny days tease our senses. We long for spring, but these are some of the brownest days of all. 

Perennial stems, once tall and straight even in death, have collapsed under the rains and cold nights. Their ragged, soggy limbs lie crumpled against the withered leaves of fall.

Sparkling rays of sunshine fall on empty seed capsules, highlighting their vacant vessels. Their job is done and their emptiness has a beauty of its own. After all, the capsule is a testament to their fertility.

Hibiscus coccineus capsule

Among the brown, in Georgia, there are spots of green. They are plants that never really go away; they are just dozing in the sunshine. I’m sure they are gathering energy; I've never known nature to let good stuff go to waste.  

A Christmas fern (Polystichum acrostichoides) here, an ebony spleenwort (Asplenium platyneuron) there … plus a scattered assortment of perennial herbs like green and gold (Chrysogonum virginianum) and the leafy rosettes of cardinal flower (Lobelia cardinalis).  

Tiny Christmas fern in the grass

I am glad to have the green, but by now I yearn for more than that. I want flowers. I want flowers, not just for themselves but for the rest of life that they bring. With flowers come insects: bees, butterflies, moths and caterpillars. Even flies (flower flies, that is) would be welcome. With insects come birds in abundance. The whole place comes alive!

A few more brown days I must endure. Nature comes in her own time, but … I just saw a single trout lily leaf (Erythronium umbilicatum) poking through the pine straw. The end of brown is near.

Sunday, February 1, 2015

A Native Tree Is Not Just A Tree

It’s an ecosystem. It is more than just a collection of leaves, flowers and fruit. It is more than just a giver of shade and large limbs for swings. It is a home and giver of life to more than we even know.

Years ago we all learned that trees are an important source of oxygen. They take in carbon dioxide that we breathe out and give us oxygen in return. They also help clean pollution from the air. Learning this was like learning about magic. What an easy thing to do! We were all excited about planting trees to improve the Earth.

People went about happily choosing and planting trees. They planted them in their yards and in their schools. City parks and median strips were strewn with these oxygen machines. It was a glorious time. Nurserymen found exciting new choices to offer their customers - exotic plants from around the world. In my childhood city, crepe myrtles were all the rage and the city planted them everywhere.

New oak leaves ready to support insects
A few people knew that not all choices were equal. You see these places where we were planting our new trees were once home to forests of indigenous trees. Oaks, maples, hickories, and chestnut once ruled the land. Their foliage and flowers were the food and sustenance for thousands of native insects.

Native plants evolved with the native insects and scientists find more evidence every year that those insects largely can’t live on non-native plants. Now you might think that fewer insects is a good thing … until I remind you that butterflies are those insects. Remember the monarch butterfly that eats only milkweed (Asclepias) plants? When milkweed goes away so do those beautiful butterflies. 

Bird food!

Every plant species has an insect or two - or even 534 of them – that depends on them.

The mighty oaks that once lived here in vast tracts support 534 different species of moths and butterflies … that we know about. There may be more. 

Birds are very fond of those insects. Many birds eat insects as part of their diet. Many more feed them to their babies. I read a great article recently about research on a common backyard bird and its relationship to suburban/urban landscapes. From the article:

Contrary to what many people believe, “birds do not reproduce on berries and seeds,” Tallamy says. “Ninety-six percent of terrestrial birds rear their young on insects.” Because native insects did not evolve with nonnative plants, most lack the ability to overcome the plants’ chemical defenses and cannot eat them.

When we're choosing our trees, most of our trees, we need to consider not just our desires but the needs of the rest of our local world. We can choose trees that feed the local insects who in turn feed the local birds. The tree's fruit (or nuts) might also feed local mammals, and of course everything might become prey for the next member of the food chain.

It's a choice that we can all make, right in our yards and in community projects, and it has an immediate positive benefit. From the moment you plant it, the benefits begin for the insects.

By the way, I am glad to hear that my childhood city is changing. I read recently that the city is gradually replacing those crepe myrtles with other species, such as maple, dogwood, crabapple or sweet bay, in an effort to diversify its tree selection. The reasoning given was to reduce disease potential as well to incorporate more native species.

We all can learn again not just that trees are important but their importance is MORE than just oxygen and shade. Their role in the insect world is every bit as important. Arbor Day is coming up this month in Georgia; this year think about planting a native tree.