The Great Giant Flea Hunt
The New york time
The New york time
GIG HARBOR, Wash. — In the Pacific Northwest, we live among behemoths — snowcapped volcanoes, towering trees, great splashing salmon and lattes as big as a child’s head. Yet one of the region’s undeniably superlative titans has slipped beneath everyone’s radar.
The land of Bigfoot and Starbucks is also home to the world’s largest flea. The flea, Hystrichopsylla schefferi, is an awe-inspiring colossus that can reach nearly half an inch, its head alone the size of a cat or dog flea. Until last month, however, there existed not a single confirmed photograph of a live member of the species.
Never mind that with ubiquitous digital cameras, the documentation of life has exploded, or the fact that the flea lives on the mountain beaver, Aplodontia rufa, a species so abundant in forests and gardens around here that it is considered a pest.
Still, for long years, this gaping hole in the world’s biological record remained of little consequence to pretty much everyone. Then my husband, Merrill Peterson, a biologist and curator of the insect collection at Western Washington University in Bellingham, began writing a photographic field guide to the insects of the Pacific Northwest (to be published in 2015 by the Seattle Audubon Society). Fleas are insects, and Merrill became obsessed with getting a photograph of the world’s largest for his book.
He found drawings and dead specimens of the flea, which has been known to scientists since 1919, but no photographs of a live one. Photographs labeled “Hystrichopsylla schefferi” can be found online, but the specimens shown are small enough to possibly be a different flea species. To authenticate them as members of the biggest species would have required examination of minute details like the presence or absence of tiny hairs at the base of the hind legs.
Unfortunately, the photographer no longer had the specimen. And though he continued to try, Merrill could not find a definitive photograph of this six-legged monster, dead or alive, anywhere.
And that is how I, an asthmatic writer, ended up with my lips on a flea-collecting device powered by sharp inhalation, watching, terrified, while Merrill, a man deeply averse to touching most mammals, wrangled a toothy, clawing wild mountain beaver inside of a basmati rice bag.
One might wonder how the world’s largest flea evolved here. Something in the water? Biologists have long argued over what might lead to the evolution of large size. The evolutionary principle called Bergmann’s rule suggests that body sizes tend to be bigger in colder climates. Also, organisms on islands can have a tendency toward gigantism. But the Northwest is mild, and the flea happily inhabits the mainland.
Then there’s Cope’s rule, also much argued, that newer groups in any given lineage tend to be larger, while the more ancient tend to be smaller.
But the mountain beaver is considered the most ancient of rodents, and therefore is likely to carry among the most ancient of rodent fleas. So why are these presumably ancient parasites the giants among fleas? Hystrichopsylla schefferi, it seems, avoids easy answers as adeptly as it has avoided the camera.
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Enlisting a Mountain Beaver
So how to find the world’s largest flea? First, find mountain beavers. Though ubiquitous, they are not easily pinpointed, it turns out. They make their presence felt during the wee hours, when they emerge from their burrows to eat, especially ferns and seedlings like newly planted firs. But they are so secretive — spending most of their lives digging long, winding tunnels — that people often don’t know it’s mountain beavers that have done the damage.
Luck came in the form of a good friend and biologist, Peter Wimberger, whose colleague Bob Peaslee, the science support engineer at the University of Puget Sound, lives on land in Gig Harbor overlooking the sound. Its steep hillside is plagued with mountain beavers.
The original plan did not involve any contact with a mountain beaver. Unlike many parasites, this flea spends time off its host and can sometimes be found in the nest material. Merrill and Peter set out with a group of undergraduates excited to spend a Saturday digging out mountain beaver tunnels on a nearly vertical bank. But many hours, many shovelfuls, and not a few beers and chips later, there was no sign of nest or flea.
He found drawings and dead specimens of the flea, which has been known to scientists since 1919, but no photographs of a live one. Photographs labeled “Hystrichopsylla schefferi” can be found online, but the specimens shown are small enough to possibly be a different flea species. To authenticate them as members of the biggest species would have required examination of minute details like the presence or absence of tiny hairs at the base of the hind legs.
Unfortunately, the photographer no longer had the specimen. And though he continued to try, Merrill could not find a definitive photograph of this six-legged monster, dead or alive, anywhere.
And that is how I, an asthmatic writer, ended up with my lips on a flea-collecting device powered by sharp inhalation, watching, terrified, while Merrill, a man deeply averse to touching most mammals, wrangled a toothy, clawing wild mountain beaver inside of a basmati rice bag.
One might wonder how the world’s largest flea evolved here. Something in the water? Biologists have long argued over what might lead to the evolution of large size. The evolutionary principle called Bergmann’s rule suggests that body sizes tend to be bigger in colder climates. Also, organisms on islands can have a tendency toward gigantism. But the Northwest is mild, and the flea happily inhabits the mainland.
Then there’s Cope’s rule, also much argued, that newer groups in any given lineage tend to be larger, while the more ancient tend to be smaller.
But the mountain beaver is considered the most ancient of rodents, and therefore is likely to carry among the most ancient of rodent fleas. So why are these presumably ancient parasites the giants among fleas? Hystrichopsylla schefferi, it seems, avoids easy answers as adeptly as it has avoided the camera.
Continue reading the main story
Enlisting a Mountain Beaver
So how to find the world’s largest flea? First, find mountain beavers. Though ubiquitous, they are not easily pinpointed, it turns out. They make their presence felt during the wee hours, when they emerge from their burrows to eat, especially ferns and seedlings like newly planted firs. But they are so secretive — spending most of their lives digging long, winding tunnels — that people often don’t know it’s mountain beavers that have done the damage.
Luck came in the form of a good friend and biologist, Peter Wimberger, whose colleague Bob Peaslee, the science support engineer at the University of Puget Sound, lives on land in Gig Harbor overlooking the sound. Its steep hillside is plagued with mountain beavers.
The original plan did not involve any contact with a mountain beaver. Unlike many parasites, this flea spends time off its host and can sometimes be found in the nest material. Merrill and Peter set out with a group of undergraduates excited to spend a Saturday digging out mountain beaver tunnels on a nearly vertical bank. But many hours, many shovelfuls, and not a few beers and chips later, there was no sign of nest or flea.
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