Scientist explains disappearance of locusts
TORRINGTON – The type of locusts which ravaged North America in the 19th century may not have been the same species as the ones from the Bible, but they might have been just as detrimental to the land. Which begs the question: where did they go?
The Goshen County Historical Society hosted a presentation on Rocky Mountain Locusts on Tuesday.
The Goshen County Historical Society hosted a presentation by Scott Schell, an etymologist at the University of Wyoming, on Tuesday about the relation between locusts and grasshoppers and possible theories of where the locusts may have gone.
Grasshoppers are from the family Acrididae in the order of Orthoptera with the main characteristic being large hind legs for jumping. Schell said there is a lot of variations as there are more than 400 species just in Wyoming. The vast majority are not harmful, but Schell added there are about 12 species still around today which still cause problems.
“They can eat more than their body weight daily and then some of the species when they walk up to a blade of grass they clip it, eat what they want and drop it making it unavailable,” Schell said.
The majority of grasshoppers in Wyoming spend the winter in eggs before hatching out in the spring. The Migratory Grasshopper is the biggest pest in the state which can go from a density of three per square yard to more than 35 per square yard in one year, according to Schell.
The periodical cicadas are often referred to as locusts as well, but Schell said they are totally different insects.
“They have a piercing sucking mouth part to suck on the fluid of plants rather than chewing mouth parts to eat leaves like a grasshopper does,” he said.
Schell said the theory of why these cicadas are referred to as locusts is because when the pilgrims first heard them, they thought the insects were saying “pharaoh,” like the plague of locusts from the Bible.
Schell stated there are many species of grasshoppers which specialists consider locusts. According to Schell, higher population densities of grasshopper species cause a “Dr. Jekyll and Mr. Hyde” type change through interactions which cause a chemical reaction of expression of genes.
The Rocky Mountain Locust is believed to be the only locust species found in North America although Schell said the Migratory Grasshopper comes pretty close. However, Some researchers believe the locusts genes remain in the Migratory Grasshopper waiting to be released. The Migratory Grasshopper species currently is widespread and can be found almost everywhere across the country.
In terms of the collections of locusts in museums they are fairly rare, according to Schell, as he was only aware of about 600 specimens. Schell said while it may seem like a large number, it is actually quite small when considering they need to collect a male and female of each species as well as multiples of species to show variations. Schell said specimens can also be lost at museums either by accident or carpet beetles which eat dead and dried insects.
The Rocky Mountain Locusts are the cause for many programs in place today, Schell said, such as the Animal and Plant Health Inspection Service which is charged by and act of congress to help with grasshopper control. The large-scale destruction cause by Rocky Mountain Locusts called action to be taken place on a national level.
Schell talked about Charles Valentine Riley who was put in charge of the Etymological Commission to solve the Rocky Mountain Locust problem in the 1870s. Schell said Riley’s work helped save the California orange and French wine industries.
The last known specimens of Rocky Mountain Locusts were collected in Manitoba, Canada in 1903 after being a major pest in North America.
Schell said the locusts were very good flyers which led to them freezing on mountainsides and in glaciers. In 2004, Schell went to the Wind River Range and collected his own specimen at Grasshopper Glacier. Finding material can be very tricky due to the constant moving and melting of the glaciers.
Schell answered questions about the largest swarm ever recorded which was 110 miles wide and 1,800 miles long. Schell said a telegrapher in Portsmouth, Nebraska, on the Union Pacific Railroad in 1874 telegraphed in all directions to telegraph stations in order to find the furthest extent of the swarm and then focused his telescope up to find the top before focusing it straight out to find the exact distance of the depth. The documentation was accepted by the Guinness Book of World Records.
Schell also talked about theories for how such a large population of a species could be wiped away. One theory is the locusts had a critical habitat to sustain the population which may have been inadvertently made unsuitable by humans.
Since there is no exact answer as to how or if locusts are extinct in North America, the research allows for anyone to form their own opinion.