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Column: Wild Neighbors: Antioch Dunes — Rare Insects of an Inland Island

By Joe Eaton
Tuesday April 01, 2008
Antioch Dunes evening primrose with unknown insect.
Ron Sullivan
Antioch Dunes evening primrose with unknown insect.

Mark your calendars: the annual spring surveys of endangered wildflowers at the Antioch Dunes National Wildlife Refuge are coming up. This year’s dates are April 9-10 for the Contra Costa wallflower and May 14-15 for the Antioch Dunes evening primrose.  

You don’t have to be a trained botanist to participate. You just need to be able to identify these showy plants (not a problem), use a clicker to tally your observations, and walk a straight-line transect without stepping on any rarities. Ron and I did it last year, and highly recommend it. For more information, contact U.S. Fish and Wildlife Service manager Susan Euing at (510) 521-9624, or susan_euing@yahoo.com. 

This place, which has fascinated me for years, is the first (and so far only) federal wildlife refuge established for plants and insects. It protects a remnant patch of sand that was scoured off the Sierra by glaciers some 40,000 years ago and deposited by the wind. The wallflower and the evening primrose evolved into distinct species here, hundreds of miles from their nearest relatives, and  

occur nowhere else in the wild. 

That’s also true of the refuge’s third marquee species, the Lange’s metalmark butterfly (Apodemia mormo langei), a northern outlier of a mostly tropical family. The metalmarks have their own survey, in later summer during the adults’ brief flight season. They spend the rest of their life cycle as larvae, either noshing on naked-stem buckwheat, their only food plant, or waiting out the dry months in a dormant state. 

In an evolutionary sense, the dunes are like an island on the land. Like the Galapagos or the Canaries, they have their suite of unique species, many of them insects. During World War II, entomologists at UC Berkeley found their field trips curtailed by gasoline rationing. The Antioch Dunes were about as far from Cal as they could get. So, making a virtue of necessity, they did a thorough inventory of the dunes’ insect life, and described a bunch of new species. I’ve been told that the scientists adopted one of the local watering holes during the war years. An entomologists’ bar is something I wish Gary Larson had drawn. 

For some reason, Life magazine, of all venues, showcased the insects of the dunes in a 1957 article, with foldout paintings by the German artist Walter Linsenmaier. (I’ve been rummaging through piles of old magazines in antique stores for years, hoping that issue would turn up, but no luck.) Growing up in Little Rock in the ’50s, I found the old Life, with its earth-history, evolution, and human-origins series, a window on a larger world. Lord knows I wasn’t getting that stuff in school; this was still post-Snopes and pre-Sputnik. 

Sadly, many of those unique species haven’t been recorded for decades. The dunes have been subject to many abuses, beginning with large-scale sand mining. Dune sand went into the bricks that rebuilt San Francisco after the 1906 earthquake and fire. Parts of the dunes became vineyards. Even after federal protection began in 1980, the area was vulnerable to fires and vandalism. The refuge was closed to the public (except for docent-led tours) after 1986, when fans of Humphrey the errant whale trampled the rare plants. 

A Nature Conservancy source lists some of the casualties: the Antioch Dunes shieldback katydid (Neduba extincta), the Antioch cophuran robberfly (Cophura hurdi), the Antioch sphecid wasp (Philanthus nasalis). These creatures vanished long before there was any kind of endangered species process. They would have been out of luck with the California Endangered Species Act anyway, since it precludes the listing of insects. 

But the insects are not all gone. It turns out that the specialized pollinator of the Antioch Dunes evening primrose—a solitary bee called Sphecodogastra antiochensis—is still around. It’s another Dunes endemic, a member of a bee genus associated with evening primroses. The nearest relative of S. antiochensis occurs in Merced County, 70 miles to the southeast of Antioch. 

These bees fly around sunrise and sunset. As their flight season progresses, they forage for pollen in the morning and nectar in the evening. Efficient collectors, they can gather a full pollen load in less than a minute. The pollen is used to provision larvae in wax-lined brood cells in the dune sands, although it appears that the larvae can develop without evening primrose pollen. A single female may establish as many as 31 cells.  

S. antiochensis has no protected status, but the Xerces Society—an estimable organization dedicated to the conservation of insects and other invertebrates—includes it in its Red List of endangered pollinating insects. For now, its survival may depend on the FWS personnel and volunteers who plant out nursery-raised evening primroses to augment the natural population. Antioch Dunes, like many other threatened places, must be tended like a garden-bees and all.