Swat team: scientists track humongous number of flying bugs

Counting the number of bugswhizzing high overhead annually may seem all but impossible, butresearchers in Britain have completed the most comprehensivetally ever conducted. And the headcount they came up with wasalmost un-bee-lievable.

A total of 3.5 trillion insects weighing a combined2,900tonnes migrated annuallyover a region in south-centralEngland monitored with specialized radar and a balloon-supportedaerial netting system, the scientists said on Thursday.

"High-altitude aerial migration of insects is enormous,"said University of Exeter entomologist Jason Chapman, whoseresearch was published in the journal Science. "These aerialflows are an unappreciated aspect of terrestrialecosystems, equivalent to the oceanic movements of planktonwhich power the oceanic food chains."

The researchers tracked the migration of insects ataltitudes between 150 and 1,200 metres over a 10-year period. They suspect even more migrating bugscould be found elsewhere.

"The numbers will be considerably higher in most parts ofthe world, but we lack the data to extrapolate the total numbersyet," Chapman said.

In terms of biomass, the insects greatly exceeded migratorybirds in Britain. Their biomass was seven times that of the 30million songbirds flying from Britain to Africa each autumn.

While the study did not plot the departure and destinationpoints for the migrating bugs, they were thought to be travelingback and forth numerous kilometres, and sometimes over theEnglish Channel and North Sea.

"Some of the butterflies and moths we studied migratehundreds of kilometres in each generation, and thousandsof kilometresover the course of the year, whichmay include six generations," Chapman said.

'We could not function without them'

Insects play important roles, pollinating plants,facilitating productive soil through decomposing, serving asfood sources for birds and bats, spreading disease, and servingboth as crop pests and predators of crop pests.

"We could not function without them," Chapman said.

The mass insect migrations generally headed north in springand south in autumn.

The most abundant day-flying insects in the study includedcereal aphids and the tiny parasitoid wasps that attack them.The most abundant medium-sized day-flying insects includedhoverflies and ladybirds, also called ladybugs, and the mostcommon big ones included large butterflies such as the paintedlady.

At night, abundant small insects included midges andother flies, while medium-sized ones includes lacewings andlarge ones included noctuid moths and hawkmoths.