Jeffrey A. Lockwood

They darkened the skies. People couldn’t even begin to imagine how many there were. And if you went back in time and said they would be extinct in 50 years, they would have locked you up.


No, not Ectopistes migratorius; Melanoplus spretus.


Jeffrey Lockwood teaches natural science and humanities at the University of Wyoming; his particular science specialty is entomology, and within that, grasshoppers. He’s written a slightly uneven but generally good account of the Rocky Mountain Locust, a creature you’ll be familiar with if you’ve ever read Giants in the Earth or On the Banks of Plum Creek. The most famous swarm, nicknamed “Albert’s Swarm” after Signal Corps meteorologist Albert Cline, contained around 3.5 trillion locusts. Given that it was 1875, one might suspect panicked exaggeration, but Dr. Cline was a pretty meticulous observer. He telegraphed other weather stations to find out if they were also experiencing a plague of locusts to get the length; timed locust velocity (around 15mph) and passage time to get the width; and estimated the depth of the swarm by turning a telescope upward and focusing until he could see individual locusts, then turning it horizontally and finding a terrestrial object of known distance that was also in focus. The swarm was 1800 miles long, 110 miles wide, and one quarter to one half mile deep. So around 200K cubic miles of locusts. Dr. Cline commented “This is utterly incredible, but how can we put it aside?”


People on the ground were understandably more than a little freaked out. The locusts ate crops. And weeds. And trees. And wool, leather and cotton when they ran out of greenery. (No one mentions anthropophagy, but there are some reports of bites, and I certainly wouldn’t want to be trapped motionless under something like that). Predators had a field day, of course, but chicken meat was supposedly rendered foul-tasting by locust consumption, and turkeys ate until they died.


And then, seemingly, that was that. There were smaller but still devastating swarms afterward, but they tapered off, and the last known swarm of Melanoplus spretus was reported from Canada in 1902. Individuals were reportedly collected as late as the 1930s, but locust taxonomy depends on configuration of the genitalia and surviving pinned specimens often aren’t sufficiently intact to verify species.


Lockwood gets a little digressive here, recounting the history of American economic entomology. There are some interesting characters here, as with all 19th century science, but this section drags a little. Things pick up somewhat with a discussion of locust taxonomy and ecology (surprisingly, perhaps, as taxonomy is usually pretty dull for nonenthusiasts). Work in Russia and South Africa had demonstrated that locusts there had a complicated life history. The ordinary forms looked like more or less typical grasshoppers, but careful research found that crowding and exposure to locust feces could induce generation of a swarming phase that looked so different it had previously be considered a distinct species (living locusts didn’t change, but the next batch out of the eggs did). Naturally, it was assumed the North American form was similar, and entomologists in the 1930s to 1950s spent quite a bit of time trying various combinations of crowding, temperature, humidity and whatnot on caged populations of Western grasshoppers trying to get them to change into locusts. Didn’t happen; apparently the Rocky Mountain locust didn’t go through phases.


Lockwood then recounts his own research efforts, trying to find frozen Melanoplus spretus in various glaciers in the American west to see if he could get usable DNA and recognizable genitalia. He was eventually successful, discovering to some surprise that the closest related species based on molecular data was rather distant based on physical characters. Lockwood expresses a little sour grapes here; he had quite a bit of trouble getting his research funded and published; one journal editor sent his submission back snarking he was “confusing natural history with science” because his work was descriptive rather than experimental. (His funding all came from private sources; although he doesn’t comment on it I can imagine what would happen if a US Congressperson discovered the NSF was sending people on hiking trips in the Rockies to study frozen grasshopper penises). Eventually, though, he presented enough data that the current paradigm in Rocky Mountain locust research is that Melanoplus spretus was a unique locust species that was responsible for the 19th century swarms; that it is not a swarming phase of an otherwise familiar grasshopper; and that it is now extinct.


The explanation for the sudden decline and extinction is plausible but not proven. Lockwood speculates that the locust may have had refugia habitat in the Rockies – somewhat similar to Monarch butterflies, where 95% of the population migrates to a few groves of trees in the mountains around Mexico City. A couple of unscrupulous loggers could destroy almost all the butterfly population in a few days. The theory is that Melanoplus spretus depended on specific soil types in a few Rocky Mountain valleys to sustain a population between swarms, and once those areas were destroyed by mining or grazing or agriculture that was it. To his credit, Lockhart is not a sentimental environmentalist of the “only Man is vile” school; he points out that there is no “balance of nature” that “Man” is somehow responsible for maintaining and that locusts have to play the cards they draw in the natural selection sweepstakes just like everything else. (In fact, he suggests that if a relict population of Melanoplus spretus was discovered somewhere, it might be perfectly justifiable to wipe it out, on the grounds of the potential damage a 21st century swarm could do). There is a little grumbling about global warming, which seemingly doesn’t fit well with the previous statement; yet there is some personal justification here as the “Grasshopper Glaciers” of the Rockies are disappearing fairly rapidly – a couple of tons of soggy locust corpses weather out every season – and they are vital to Lockwood’s research. I was prepared to make a standard argument here – if things are melting out of glaciers now, that implies that at the time they froze into the glacier the glacial extent must have been about the same as it is as present; however Lockwood anticipates that (although not explicitly) by noting that things can migrate through glacial ice from their initial position. Not quite sure if that can be done with well-preserved grasshopper bodies, but I’ll give it the benefit of the doubt.


Lockwood concludes with a tantalizing hint that just maybe the story isn’t over; he examined a few grasshoppers in Yellowstone National Park that didn’t quite fit the morphological profile of anything but Melanoplus spretus. Having no collecting permit, he wasn’t able to dissect them and examine the genitalia; however, they were in exactly the type of high valley that he speculated was the refuge habitat for the Rocky Mountain Locust. And, of course, Yellowstone, established when there were still massive locust swarms, was never grazed or mined or farmed or whatever it was that did in the other supposed habitats.


A bit disappointing in the illustration department; Lockwood uses only 19th century drawings of the species, its habits, and its presumed range. I would have liked to see a little more explanation of how DNA analysis works and some pictures of the characteristic genitalia (especially because the text refers to parts by their technical names). The bibliography is short but useful; however there are no reference notes in the text. As mentioned, the chapters about early North American entomologists drag a little. Still an engaging read.… (más)

Who can resist a title like this? I thought this would be just a curious and funny subject, but it is fascinating, very well written, and I learned a TON about history and bugs. The humans are far creepier and more disgusting than the insects are. Even the footnotes are not to be missed, and the suggested reading well organised. No doubt Lockwood is a favourite professor with Natural Science and Humanities students at the University of Wyoming, as his abilities to be simultaneously educational, interesting, accessible, and discussion-provoking are flawless. Warning: if you read this in the presence of another person, you might become the type that is constantly interrupting with, "Oh my god, listen to this!" However, you can have confidence that whatever you share with them from this book will elicit so many "Whoa!"'s and "No way!"'s that eventually if you even whisper "Damn..." under your breath, they will demand to know what you just read.… (más)