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Many dragonflies, beetles, butterflies, locusts and moths are known to migrate during the breeding season and the distance travelled varies with species. Most insects travel in large groups and scientists have been studying these movements for several years.
A recent study ( PNAS ) noted that the painted lady butterfly (Vanessa cardui) can make 12,000 to 14,000 kilometre round trips. This is the longest annual insect migration circuit so far known.
Found in sub-Saharan Africa, the butterfly is able to travel to Europe, crossing the Sahara Desert when weather conditions are favourable. The caterpillars thrive in wetter winter conditions of sub-Saharan Africa and the adults migrate to North Africa during wet spring. They then cross the Mediterranean Sea to reach Europe.
Simulations in the laboratory showed that favourable tailwinds between Africa and Western Europe help these insects in transcontinental travel. They fly about one to three kilometres above sea level with a maximum speed of around 6 metres per second. The researchers studied a similar butterfly species and calculated that the painted lady may have enough body fat to sustain 40 hours of non-stop flying.
