It’s been a while, Carl Zimmer! Welcome back to our pages and thanks for this new consideration of what is included in the definition of animal migration, a pair of words normally associated with big mammals and birds:
Swarms of insects move across continents each year. Scientists used radar to track one species and discovered a vast ecological force.
Ladybugs briefly took over the news cycle.
Meteorologists at the National Weather Service were looking over radar images in California on the night of June 4 when they spotted what looked like a wide swath of rain. But there were no clouds.
The meteorologists contacted an amateur weather-spotter directly under the mysterious disturbance. He wasn’t getting soaked by rain. Instead, he saw ladybugs. Everywhere.
Radar apparently had picked up a cloud of migrating ladybugs spread across 80 miles, with a dense core ten miles wide floating 5,000 feet to 9,000 feet in the air. As giant as the swarm was, the meteorologists lost track of it. The ladybugs disappeared into the night.
Compared to other animal migrations, the migrations of insects are a scientific mystery. It’s easy to spot a herd of wildebeest making its way across the savanna. Insects, even in huge numbers, move from place to place without much notice. One day you look around, and ladybugs are everywhere.
“The migrations themselves are totally invisible,” said Jason Chapman, an ecologist at the University of Exeter in Britain.
Dr. Chapman and his colleagues are using radar to bring insect migrations to light. The scientists help run a unique network of small radar stations in southern England designed to scan the sky 24 hours a day, spotting insects flying overhead.
“These radars are fantastic,” said Dr. Chapman. “We have a lot of information about every individual insect that flies over overhead, including a measure of the shape and a measure of their size.”
Recently, Dr. Chapman and his colleagues decided to scan their images for one kind of insect in particular, known as hoverflies…
Read the whole story here.