Pollinators Make it Happen
“Earth laughs in flowers.”
And Pollinators Make it Happen!
HELM Network News by Christine Middleton
Have you noticed all the beautiful wildflowers popping up around your property? Most depend on animals to move their pollen around so that we can enjoy flowers again next year. Butterflies, bees, and hummingbirds aren’t their only pollinators. Beetles, flies, and other insects also move pollen from flower to flower. Most pollinators seek flowers for their sugary nectar. Then, inadvertently, they carry pollen from one flower to another. Most pollinating beetles don’t feed on nectar, preferring plant parts instead. But they too accidentally carry pollen along with them in their search for food. While bees do feed on nectar, they are also one of the few flower lovers that actively seek pollen—they collect and purposefully transport the pollen to feed their young. Ants, wasps, flies, and mosquitoes also pollinate some flowers. And night blooming flowers generally depend on bats and moths. Land stewards appreciate the role pollinators play in maintaining the health of their property through the important ecosystem services they provide.
Food for Caterpillars
Everyone loves butterflies, so let’s start there. Butterflies are caterpillars before they turn into beautiful winged creatures. And female butterflies choose where to lay their eggs based on what their caterpillars need to eat once they hatch. Just as there are lots of different butterfly species, there is a wide range of native plants that host caterpillars. Some butterflies and moths are polyphagous, meaning they utilize a variety of different host plants. But others are considered oligophagous, meaning they depend on a limited number of larval hosts and sometimes just one specific species. So the absence of that specific plant or plant group can mean that that particular species of butterfly and its caterpillars won’t be present in that area’s ecosystem.
You’re probably thinking right now about Monarch butterflies and Milkweed, so hold that thought. Have you seen any milkweed on your property this year? The fact that monarchs need milkweed as they migrate north from their winter home in Mexico is widely understood. You are probably familiar with the first milkweed pictured below—Antelope Horns (Asclepias asperula). Also here are two less conspicuous milkweeds HELM has observed growing wild on properties we’ve visited. The second picture shows its green star-shaped flower with a pearl-like center that gives this species its common name, Pearl Milkweed Vine (Matelea reticulata). The final milkweed is Zizotes Milkweed (Asclepias oenotheroides). Zizotes Milkweed has shallow roots, but it can survive droughts. After it finally starts to rain, Zizotes Milkweed leafs out and flowers. There are more species of milkweed native to Central Texas. Here’s a link to the Lady Bird Johnson Wildflower Center’s list.
Lots more caterpillars hatch than make it to adulthood because they are quite a nice juicy snack. You may notice all sorts of bugs nibbling on your Antelope Horns. Is that a problem? A recent study suggests popularity may be a good thing. Scientists studying such things were actually surprised to find that monarch caterpillars are more likely to survive on milkweed they share with other non-predatory insects. While that sounds counterintuitive, it actually makes sense. If potential predators have more to choose from, a larger number of monarch caterpillars survive long enough to go through metamorphosis and delight us by turning into butterflies.
But let’s not limit our thinking to just Monarch caterpillars. There are lots of other kinds of caterpillars, only some of which will become butterflies—many turn into moths and skippers. But why are caterpillars so important? Environmentalist Doug Tallamy observes in his book Nature’s Best Hope, “Caterpillars are the mainstay of most bird diets in North America, particularly when birds are raising their young.” Tallamy points out that most of a caterpillar body is digestible food; caterpillar bodies are more nutritious than other insect bodies. You could say caterpillars provide more bang for the buck. For example, one caterpillar is equal to 200 aphids. And think about this: many birds forcefully stuff food down a nestling’s throat—something more easily (and more comfortably!) done with soft caterpillars than with a beetle’s hard exoskeleton.
You might be surprised by the wide range of plants that host caterpillars. Ashe Juniper (Juniperus ashei), which we covered extensively in our last newsletter, is host to Juniper Hairstreak butterflies. Twistleaf Yucca (Yucca rupicola) hosts two species of Giant Skippers. Texas Thistle (Cirsium texanum) is host to Painted Lady and Mylitta crescent butterflies.
And don’t just focus on flowering plants. Oak trees host the most caterpillars—a total of 486 different species in our area. In terms of flowering forbs, the lead contenders are goldenrods (Solidago, 82 species) and sunflowers (Helianthus, 81 species). We could go on. A good reference is Native Host Plants for Texas Butterflies: a Field Guide, by Jim Weber, Lynne Weber and Roland H. Wauer.
Twoleaf Senna - photo by Wynn Anderson - Courtesy of the Wildflower Center.
Here’s one host plant you might see flowering on your property: Twoleaf Senna (Senna roemeriana). The plant is pretty inconspicuous—no more than 1-2 feet tall. But it is relatively easy to identify even if it is not flowering. That’s because Twoleaf Senna has very distinctive leaves divided into just two leaflets as its name suggests. Twoleaf Senna hosts Sleepy Orange and Cloudless Sulfur butterflies, two of the little yellow butterflies we often see. And this plant has an added benefit. It’s a member of the Pea family, which means it is a nitrogen fixer. And as every good gardener knows, nitrogen fixers are good for the soil.
To discover what other plants host lots of butterflies, skippers, and moths, click on National Wildlife Federation Native Plant Finder and enter your zip code.
Pollinator/Plant Relationships
But what about other pollinator species? Beetles have been around longer than butterflies. It is thought beetles helped shape the evolution of plant-insect pollinator relationships. Beetles don’t have specialized structures or other mechanisms for picking up pollen; the pollen grains must simply stick to their bodies as they move from flower to flower. So the plants that beetles pollinate have to produce lots of pollen—like the cactus flower in the picture. Beetles are said to be “mess and soil” pollinators because rather than looking for nectar, they eat through leaves and petals. So beetle-pollinated plants often have thicker flowers and leaves to help them survive the damage left behind.
Flower shapes also evolved with their pollinator partners. Beetles tend to favor large cup-like flowers that open during the day. Hummingbirds often favor tubular flowers. The way hummingbirds and flowers evolved together benefits both—a process called coadaptation. Hummingbirds around the world have different shaped beaks that are matched to particular flowers native to their region. In return, flowers pollinated by hummingbirds evolved to produce the rich nectar required to replace the massive calories hummingbirds burn as they hover. Those flowers’ tubular shape also protects their richer nectar from bees and other competing pollinators.
Color and smell are also what some flowers use to attract pollinators. Hummingbirds favor red, pink, fuchsia, or purple flowers. Butterflies like bright yellow, orange, pink, and red. Bright blue and violet colors are said to attract bees. But that is not always true, as evidenced by the photo of the bee on Frostweed. Nighttime pollinators, such as moths and bats, use fragrance rather than color to find flower mates. Beetles have some color vision, but they too rely principally on their sense of smell to find flowers. So the flowers beetles pollinate usually have a spicy, sweet, mushy, or fermented smell like overripe fruit.
Diversity is the Key
Why is diversity so important? There are lots of interactions among communities of species, many of which we are just now beginning to fully understand. And because everything is so interconnected, the absence of one species can have a ripple effect across an ecosystem. Pollinators are an important component in the scheme of things for many reasons, not the least of which is the fact that they facilitate the reproduction of 90% of the world’s plants. Pollinators also provide food for birds and other animals higher up the food chain. So a diversity of plants will attract a diversity of pollinators, who in turn will feed a diversity of baby birds…and on up the food chain.
Bee on Sotol—this and header photo: Mimi Cavender
Over the past year and a half, the HELM team has visited lots of properties scattered across Hays County. One of the things we do on a HELM visit is identify as many of the plants growing on the property as we can. Sometimes we are pleasantly surprised and pleased with the diversity of plants growing on a particular property. Other times we find ourselves a bit dismayed when we find far fewer species. Knowing what is growing on your property is an important first step toward good land stewardship.
We can help. If you would like the HELM team to visit your property, identify some of the plants growing there, and teach you to use iNaturalist so you can easily grow your knowledge at your own pace throughout the year, click here to request a visit:
The next step is knowing what species should be there and how to get them back. More on that in future newsletters.
