Migration brings to mind the exhaustive flights of migratory birds or the treks of large herds of hoofed mammals. But some insects migrate too. You may be aware of the story of migrating monarch butterflies and their mountain home in Mexico. But did you know that some of our familiar ladybird beetles of nursery rhyme fame also migrate? They really do “fly away home”?
Both in the larval stage and as adults, many species of ladybird beetles feed voraciously on aphids. Their fondness for aphids and scale insects has made them a very popular biological control agent. In 1887, a group of Australian species was imported into California to deal with an Australian scale insect that was devastating the citrus crop. These ladybird beetles were the first exotic insects to be introduced into North America for use as biological control agents. Within a year, the citrus crop was saved.
Ladybird beetle larvae hatch in the spring and devour aphids for about a month. They then pupate and soon emerge as adults. If there are insufficient aphids to feed these adults, they fly away, migrating to overwintering sites in the mountains. There they eat pollen to build up fat reserves. Ladybird beetles use the wind to loft their migration; waiting for a strong breeze in the correct direction before departing. As winter approaches in their mountain retreats, they congregate in the thousands, aided by the release of an olfactory attractant. If you are lucky in your mountain travels, you may come across one of these amazing masses of bright red beetles.
Come spring, they will mate, take wing and descend to their lowland aphid feasts, thus completing the cycle.
Our theme music was composed by Don Anderson and is performed by Leaping Lulu.
This is Linda Kervin for Bridgerland Audubon Society.
Photos: Courtesy US NPS Sally King Photographer,
Text: Linda Kervin & Jim Cane, Bridgerland Audubon Society
Theme Music: Don Anderson & performed by Leaping Lulu,
Peter J. Marchand, Autumn: A Season of Change (Hanover, NH: University Press of New England, 2000)
Arthur V. Evans & Charles L. Bellamy, An Inordinate Fondness for Beetles (Berkeley, CA: University of California Press, 1996)