Backyard Biodiversity
As you read this, the Natural History Museum’s Entomology Department is collecting insects in the rainforests of Costa Rica and Thailand. But last year, Curator Dr. Brian Brown also set up a Malaise trap in a locale slightly less exotic—his Los Angeles backyard.
The trap, named not for the feeling but for its Swedish entomologist inventor, René Edmond Malaise, consists of a tent-like apparatus and an attached collecting bottle. Using it in his yard, Brown procured an assortment of familiar insects, as well as an unusual looking robber fly, about a centimeter long.
He thought little of it, but as entomologists are wont to do, he dropped it in some alcohol and handed it off to a colleague when the two were at the same biology conference in Chicago. The recipient, the Field Museum’s Dr. Torsten Dikow, is a robber fly expert. “There’s not that many fly experts,” Brown says. “We tend to know each other.”
Dikow contacted Brown a few weeks later, astounded. The backyard fly was a new species of the genus Leptopteromyia, previously known only in an area spanning from Central America to southern Texas, and certainly not from the U.S. west coast. “What is interesting about this genus,” he wrote to Brown, “is that the larvae are known to develop in webs of Embioptera — an enigmatic group known as web spinners. Do you have Embioptera in your backyard? Is there any chance you got more of these?”
In fact, Brown did have those strange web spinners in his backyard, and even better, he found several more specimens of the new species in subsequent trap samples. The flies are in a family popular with amateur collectors and had eluded capture. “Probably they are not rare,” Brown says, “just unnoticed and previously unexpected.”
For fun, and to provide a theme for a Museum special event, Brown bragged that he could find unknown fly species from other backyards as easily as his own. Last spring, he set up a trap in a Museum Trustee’s Brentwood backyard. The very first specimen he put on a slide and looked at under the microscope was a new species of the phorid flies he studies. “The second specimen I pulled out was a species that had only been found before in Europe, and then another specimen I pulled out, we identified as a species that had only been collected off the coast of Africa.”
The very first specimen he put on a slide and looked at under the microscope was a new species of the phorid flies he studies. “The second specimen I pulled out was a species that had only been found before in Europe, and then another specimen I pulled out, we identified as a species that had only been collected off the coast of Africa.”
Entomology Curator Brian Brown sets up a Malaise trap in a backyard in Monrovia, Los Angeles County. The trap has yielded new and rare insect species.
Even for Brown, this was a stunning range expansion. “Finding a fly previously known only from the coast of Africa in a Los Angeles backyard shows how little we really know about the distribution of life around the world.”
His advocacy of “backyard diversity” isn’t new. Brown first became interested in it during the Museum’s Spider Survey, which began in 2001 and invited Angelenos to bring arachnids to his department for an informal citywide inventory.
The survey found that the local eight-legged fauna had as much in common with Europe as with the surrounding wild lands. It encountered new species, new distribution records, and even the first examples of the now common (but then undetected) South African brown widow spider.
“The reaction to it was almost overwhelming at times,” Brown says. “We got over 1,000 families participating, bringing in close to 5,000 spiders. So I knew there was a lot of interest in wild life, even in an urban area like Los Angeles.”
As natural habitats increasingly become replaced by suburban development, the insect and other animal life found in gardens and other altered landscapes are increasingly the only wildlife people encounter. But if they look closely, this fauna isn’t an impoverished one. Introduced insects mix readily with native species able to thrive in the new, relatively water-rich and lush backyard habitats.
“I have seen tropical butterflies laying eggs on passionflower vine in the heart of downtown L.A.” cites Brown. “For me, it’s as typical an L.A. experience as seeing flocks of feral parrots fly over. They enrich the quality of our lives by living in our backyards.”
When Brown talks about backyards, he means two things: the area in and around our homes, and the area in and around Los Angeles. To that end, the Entomology Department recently received two small grants from the Santa Monica Mountains National Recreational Area to conduct terrestrial invertebrate inventories.
One grant will incorporate Malaise trap collections of hover flies, brightly colored wasp and bee-mimicking flies that are important pollinators. The other supports data mining inside the Museum—essentially a hunt for specimen labels from the Santa Monica Mountains that have been collected over decades.
“They know a lot about the mammals and the plants that are there, and they’ve got really finely grained vegetation surveys,” Brown says. “But they know almost nothing about the insects. We’re just trying to find out what’s there. You can’t manage natural areas if you don’t know what’s present.”
In the meantime, Dr. Dikow will describe the new robber fly and Brown will continue to explore biodiversity in backyards, both figurative and literal. “It is truly amazing,” Brown says, “how poorly known, but biologically rich, the fauna of Los Angeles can be.”