Hi, I made a trip to Washington DC in the 80's as we
passed through Virgina, they were being invaded by large locast that
looked like huge grasshoppers. So many on the highway it was
slippery on exit ramps, so loud you could not hear the radio & it
drowned out hte sound of the large trailer trucks passing by. What
was the reason for this & does it happen often? No one I talk to belives me.
When you mention that they were loud, I believe that you were seeing cicadas,
not true locusts (which ARE grasshoppers).
Some species of these tremendously loud insects have a very long life cycle:
enormous cohorts arrive every 17 years. There are so many that predators
cannot eat them all and cannot make a dent in their population. So huge
numbers of cicadas mate and lay eggs in a single summer, and the huge number
of larvae grow and grow over the next 17 years, and then the adults erupt onto
the scene once again, making the spectacle you describe. I remember it well
from my childhood in Maryland.
Richard E. Barrans Jr., Ph.D., M.Ed.
Department of Physics and Astronomy
University of Wyoming
Grasshopper outbreaks tend to be cyclical and dependant on climate and other insect
populations. Often drought conditions will encourage grasshopper outbreaks. Sunlight
and high heat and humidity discourage important grasshopper pathogens and are increase
the speed of egg/nymph/adult development. Depending on what year it was, 1988 had a
massive drought over the U.S. These conditions could have made it favorable for a
Click here to return to the Zoology Archives
Update: June 2012