Don't Dig Those Dandelions?!

Many of us conduct certain rituals in our yards and gardens without questioning why; not the least of these is "weeding." We are taught to despise any plant that volunteers itself in the flowerbed or the lawn. We are conditioned to uphold certain standards, and look to the marketplace for products to help us with that. Fortunately, the tide may be changing. Take dandelions for example.

© Marc Keelan-Bishop

I was surprised and delighted to see this meme pop up in Facebook recently, daring to suggest that we should be lazy(?!) in our approach to the inevitable blooming of dandelions.

Jewel beetle, Anthaxia sp.

In my own experience, especially in the western United States, I can vouch for the fact that a startling variety of insects exploit dandelions in early spring when few other flowers are in bloom. Birders will be pleased to know that Lesser Goldfinches and House Sparrows, at the least, feed on the seeds.

Checkered Skipper

Variegated Fritillary

Painted Lady

Dandelion, Taraxacum officinale, is an introduced species in North America, presumably brought here by European settlers in the 1600s as a food crop. Indeed, the Common Dandelion has much to recommend it in nutritional value, and herbal medicine. The greens can be eaten raw, while older leaves are best if cooked. You can brew dandelion wine; and the roots, when baked and ground, make a decent coffee substitute. The diuretic properties of the plant are well-known.

Andrena mining bee, © Elaine Mansfield

Sweat bee, Lasioglossum sp.

Sweat bee, Halictus sp.

Meanwhile, bees of all stripes take advantage of the dandelion's robust nectar and pollen supplies, and early-blooming schedule when few native plants are yet in flower. Indeed, dandelions bloom throughout the warmer months, filling voids in natural bloom cycles between spring, summer, and fall peaks.

Celery Looper Moth

Melipotis moth, Melipotis sp.

Our disdain for dandelions seems to be of a cosmetic nature, and a reminder that we are not the masters of Nature, even in our own backyard. Consequently, we turn to herbicides, which only compound our problems by killing other, desirable plants, and contaminating groundwater and streams, rivers, and lakes.

Cutworm Hunter wasp, Podalonia sp.

European Paper Wasp

Ironically, it has been demonstrated that even if you mow dandelions, they will "learn" to grow shorter, flowering at a height just beneath the lawnmower blades. Might as well learn to live with them. Just tell your guests that you still have a green thumb, but you are also promoting biodiversity.

Sources: Bradbury, Kate. 2015. "Let dandelions Grow. Bees, beetles, and birds need them," The Guardian.
Wunder, Michael. 2015. "City spares dandelions to help pollinators," The Waverly News (Nebraska, USA).
IDÉOmedia

Flower fly, family Syrphidae

Yellow Dung Fly, a predator

Tachinid fly, a parasite of pest caterpillars

(Most) Butterflies are Not Pollinators

I hate to burst your bubble, but most butterflies are not pollinators. They are eye candy. Butterflies are best described as "flower visitors" that are there seeking nectar, a carbohydrate, to fuel their flight. They could generally care less about pollen. It may actually be a nuisance that builds up on their bodies and has to be groomed off to maintain the insect's keen senses of smell (antennae), and vision (eyes). They pollinate by accident, thanks to pollen getting trapped in body hairs. Pollen grains probably clog the proboscis, too, as that "tongue" is a complex assemblage of several tubular and sheath-like mouthparts that actively pump nectar from the flower into the butterfly's digestive tract.

Painted Lady Butterfly

To be fair, there is one class of butterflies that actually eats pollen: The Heliconiinae subfamily of the brush-footed butterflies (family Nymphalidae). These are the "longwings" that are favorites in the tropical butterfly house industry. Longwings fly rather slowly, often at eye level or lower, and have a great diversity in species. There is even strong diversity in color pattern within a single species. They make near perfect display animals in captivity. They also have greater longevity as adults because they have the capacity to ingest protein in the form of pollen.

Heliconius erato longwing butterfly

Heliconius sapho longwing butterfly

When contemplating planting a "pollinator garden," prime consideration should be given to bees, hummingbirds, moths and flies. Butterflies will be attracted regardless, but the real pollinators need to be your target. Planting native species should take priority over gaudy ornamentals that too often become invasive in the natural landscape, and/or are too demanding in terms of fertilizers, pesticides, and other artificial life-support chemistry.

Sweat bee, Lasioglossum sp., on a composite flower

Tolerate "weeds!" One man's weed is another species' wildflower. Wild composites, that is, flowers in the aster family, are greatly preferred by most insects because they can visit more than one flower at one stop, reducing energy expenditures from flying blossom to far-flung blossom; and the flat surface of composites affords them a greater field of vision to watch for approaching predators. Few insects want to literally dive head-first into tubular flowers, though many bees do so all the time, and I have seen sulphur and swallowtail butterflies do so.

Black Swallowtail caterpillars do eat fennel, dill, anise, and parsley

Tolerate caterpillars! Many people fail to see the link between the butterflies (and colorful moths) they love, and the larvae they loathe. You cannot have one without the other! Planting host plants for caterpillars will arguably do more to attract butterflies to your garden than planting nectar-rich flowers. Remember, too, that plants have their own built-in chemical defenses to protect themselves; and even if defoliated, they can recover. A complete garden ecosystem with all its checks and balances in the form of herbivores, predators, parasites, fungi, soil fauna, and other organisms, is far less expensive to maintain than one that is micro-managed with pesticides and herbicides. Save time and money by choosing the right plants initially, and learning from reputable, unbiased sources what insect species are truly harmful and which are ones you can live with, if not encourage.

Leafcutter bees (Megachile spp.) will nest in holes drilled in wood blocks

Think native bees. The apiculture (honey bee) industry is a powerful lobby, and has largely convinced the general population that honey bees are the *only* bees. The overwhelming majority of bee species are native, and solitary or semi-social in their habits. Agriculture needs honey bees, no question. Your garden, and wild habitats, do not. Consider putting up bee boxes for housing our native, solitary bees. Their traditional nesting sites are being plowed under, paved over, and cut down at such a rate that they can use artificial homes.

Bundles of hollow twigs attract solitary bees that nest inside them

Lastly, I will say this for the Monarch butterfly. They are large insects, powerful enough to effectively pollinate milkweeds. Milkweeds package their pollen in sticky bags that are not easily dislodged from the flower. You can usually find bees, flies, and other insects that have become mortally stuck to milkweed flowers, unable to extricate themselves. Large wasps, large bees, and large butterflies are among the few insects able to effect the pollination of milkweeds. Learning which insects effectively pollinate which plants is also key to making your own garden or yard a "pollinator paradise."

Monarch Butterfly

Wasp Wednesday: Purslane Sawflies

Not all wasps sting, and not all feed on other insects in their youth. The larvae of sawflies are vegetarians, and many are mistaken for caterpillars. You need not venture far to find sawflies, either. I found the adult female specimen below in my own backyard on the evening of September 18. Through a little detective work I discovered she is a Purslane Sawfly, Schizocerella pilicornis, in the family Argidae.

This species is unique among all argids (worldwide) in that its larvae feed internally on the host plant, mining inside the leaves of purslane. Until recently, it was thought that some larvae of S. pilicornis feed externally. Analysis of mitochondrial DNA has demonstrated that those leaf-nibbling larvae belong to a separate species, S. lineata (Hartsough, et al., 2007).

Adult females can be distinguished by the amount of black markings on the top of the otherwise red (or orange) thorax. Females of S. pilicornis have a solid, or nearly solid, black stripe down the center of the thorax, constricted in the middle. Females of S. lineate have very reduced black markings along the midline of the thorax. S. lineate is also slightly larger, females averaging about 7 millimeters to the 5-6 millimeter length of female S. pilicornis.

Both species are widespread in the New World, ranging from southern Canada to at least Central America. S. pilicornis occurs at least as far south as Argentina. U.S. records for S. pilicornis include Arizona, California, Colorado, Connecticut, Washington, DC, Florida, Indiana, Iowa, Kansas, Maine, Maryland, Michigan, Minnesota, Mississippi, Nebraska, New Hampshire, New Jersey, Ohio, Oregon, Texas, Virginia, and Washington. The species may actually be adventives here, and native to South America. At least, it was not described from North America until 1900.

Life history information may be open to debate since it comes prior to the realization that two species are involved (Gorske, et al., 1977). Females lay one egg per leaf, inserting the ovum into the foliage with the saw-like ovipositor that gives sawflies their common name. Larvae feed for roughly six days, going through five instars (an instar is the interval between molts). Mature larvae tunnel into the soil to a depth of about 3.5 centimeters where they pupate. Adults emerge a week later (during the summer generations; otherwise they overwinter as pupae). Their lifespan as adults is apparently very short, only 24 hours according to one source (Gorske & Hopen, 1976).

There can be up to six or seven generations annually, at least in Illinois, where these insects exert a small degree of biological control against purslane.

Males in this genus are easily identified by the last antennal segment, which is forked. It looks like the insect has four antennae instead of the two it should have.

I have found numerous males, and this one female, “sleeping” out in the open on grasses and other vegetation at sunset. Many wasps (and solitary bees) can be found by looking in fields and meadows for sleeping individuals at dusk, in the early morning, or during inclement weather.

Sources: Gorske, S.F. and H.J. Hopen. 1976. “Purslane sawfly (Schizocerella pilicornis) as a biological control agent of Common Purslane (Portulaca oleracea L.),” a paper presented at the 73rd annual meeting of the American Society for Horticultural Science, August, 1976.
Gorske, S.F., H.J. Hopen, and R. Randell. 1977. “Bionomics of the Purslane Sawfly Schizocerella pilicornis,” Ann. Entomol. Soc. Am. 70(1): 104-106.
Hartsough, Chester D.B., Edward F. Connor, David R. Smith, and Greg S. Spicer. 2007. “Systematics of Two Feeding Morphs of Schizocerella pilicornis (Hymenoptera: Argidae) and Recognition of Two Species,” Ann. Entomol. Soc. Am. 100(3): 375-380.