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.
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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 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.
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.
Resigned to having to get a flea directly off a mountain beaver, Merrill sought the advice of Wendy Arjo, a wildlife biologist with Ageiss, an environmental consulting firm based in Evergreen, Colorado, who has worked often with mountain beavers.
It’s simple, she said. Trap a mountain beaver (perfectly legal). Coax it into a burlap bag, face first. Hold it just behind the jawline - not too far up, or you will be bitten; not too far back or it will get loose and then you will be bitten. Peel open the bag to reveal the hind end. Comb for fleas. Easy peasy!
Merrill’s preferred study subject is the butterfly, though he has dared to branch out to beetles. As a biologist, I studied fruit flies. Our choices were deliberate- Neither of us ever wanted to handle an animal that could pass along a disease like rabies. More important, the closer an animal gets in evolutionary relationship to a person, the less the capturing experience is like netting a wild butterfly and the more it is like trying to hold an unwilling acquaintance inside a sack.
Still, I wasn’t too worried when we set the humane traps at burrow entrances, baiting each with an apple. We’d set traps before and never caught anything. So it was with horror that I heard Merrill read a text message from Bob that we had succeeded.
Mountain beavers move easily across the line that divides cuddly and horrifying, depending on whether you find them gently grazing among ferns or coming at you with bared teeth and claws. This one was calm, sitting in the trap, surveying us as we surveyed it.
I bent down to take a photograph. The creature got up and peered back. Through the viewfinder, I saw a staring black eye and unbelievably long, sharp claws reaching out through wide gaps in the cage. I shuddered, wondering if the mountain beaver might be calm because it was well armed and we were not. Transferring this animal to a bag and trying to comb it like a pet seemed ill advised.
Much to our surprise, the mountain beaver ambled agreeably from the trap into the bag. Merrill, having donned his newly purchased gloves, closed the sack and observed the slow-moving lump, trying without success to figure out which part was the head. He made rapid, tentative grabs, sometimes getting hold of something, then losing his grip and trying to get his hand quickly away. Was that the tail? Where were the claws? Those teeth?
Does this rate with Steve Irwin’s wrestling carnivores, or bullfighters’ facing irate beasts with piercing horns? Of course not. But we are none of these kinds of heroes, just a couple of timid fools equipped not with muscles and daring and backup, but with gear from the local pet shop, the Asian food market and the dream of catching the world’s largest flea.
Eventually, Merrill got his hand behind the mountain beaver’s head and kept hold. He peeled back the bag to reveal its adorably fuzzy gray bottom, covered in short and soft hairs. He began to comb. No flea. He combed a bit more. No flea.
At which point the mountain beaver got loose. Amid my screaming, I am not sure exactly what ensued. But when I looked again, I found Merrill, eyes wide, skin pale, panting, the bag reclosed with the mountain beaver resting inside. I observed that it is possible for a person’s pupils to become so large that the irises seem to disappear.
Despite this mishap, Merrill asked me to cut away as much of the bag as possible so he could comb more of the mountain beaver. And though burlap was all that stood between us and teeth and claw, I cut.
He combed the underside of the beast. Something brown tumbled down. That’s when the love of my life - normally eloquent and articulate - began shouting, “Flea! Big flea!”
’Inhaling’ the Flea
The device hanging from my lips was an aspirator. It had a plastic vial stoppered by a rubber plug through which were threaded two thin metal tubes, with small rubber hoses attached. The end of one hose in my mouth, I held the tip of the other over the flea, where it lay amid mountain beaver fur. One quick gasp, and the bug would end up - ping! - in the vial.
I tried not to think of all the microorganisms and parasites I would be inhaling. I breathed in as sharply and deeply as I could. Nothing doing. The world’s largest flea moved about a 1/4-inch into the rubber tubing as my agitated husband, still grasping the mountain beaver, shouted, “Suck! Suck harder!”
This is an unaccountably rude-sounding thing to have yelled at you. Still, several increasingly asthmatic, panicked inhalations later, the flea was in the vial.
It is an exhilarating experience to see, in your hand, an animal that you have been talking and thinking about for months, a species so difficult to lay hands on that - however many digits and however much dignity you are willing to sacrifice - you have to assume you are never going to catch. Yet there it was, a surprisingly
There was no small amount of joyful cursing. Merrill looked ecstatic. I found myself veering between the urge to giggle hysterically and the urge to vomit.
We thanked and released the mountain beaver, who despite its ordeal, we could comfort ourselves in knowing, was living with one less bloodsucking parasite.
When we got home, I looked, for the first time, at what the authorities had to say about mountain beavers. The Washington Department of Fish and Wildlife captured the consensus, emphatically warning against ever handling these animals, which give “a very bad bite.” Did I mention that you should not try this at home?
Merrill now has scores of photographs of the world’s largest flea; it will be preserved at the insect collection he oversees at Western Washington University.
I am pleased this little adventure is over; it is a hideous thing to be terrified. But it is also a delight to know that unkempt, uncontrolled wildness lives just beyond the granite countertop and the manicured lawn.
We may never know why this patch of earth and the mountain beaver have been graced with the world’s biggest flea, the oxymoron to end all oxymorons. But we can take pleasure in knowing that this beast, this entomological paparazzi’s dream, our own superlative and wild champion, moves in mystery, always beneath our feet - and soon in a book, which may be where it best remains.