University of Exeter scientists studied the movements of migratory hoverflies and were surprised to find up to four billion migrate to and from Britain each year.

The study shows these numbers have been relatively stable over the last decade, and such abundance means migratory hoverflies pollinate many billions of flowers and produce larvae that eat up to ten trillion aphids.

Recent research has suggested more than 40% of insect species worldwide are "threatened with extinction," creating a major threat to "ecosystem services" (benefits to humans from the natural environment, such as pollination of crops).

"The number of migrating hoverflies coming and going over Britain was much higher than we had expected," said Dr Karl Wotton, Royal Society research fellow at the University of Exeter.

"They are widely considered to be the second most important pollinators, after bees.

"They are especially important pollinators of wildflowers, soft fruits and brassica crops, and their larvae prey on various species of aphids -- which are the key crop pest in Europe.

"This dual role makes them uniquely beneficial to humans."

Migrating hoverflies arrive in Britain in spring and, with a month-long life cycle, those that leave are descendants of the spring arrivals.

Read on: https://www.sciencedaily.com/releases/2019/06/190613143520.htm