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Christmas Beetles

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In Australia, Christmas beetles herald the coming of the holiday season. They are noisy, clumsy fliers that congregate near lights after the sun goes down. Despite being pests, their large size and lustrous shine intrigue people, and many Australian citizens look forward to their coming every year around Christmas time.

Christmas beetles belong to the genus Anoplognathus. There are about 35 species in Australia and South Africa, but Anoplognathus pallidicollis is the most commonly encountered. These beetles are very similar to the June beetles and May beetles that we see here in the United States. Christmas beetles range in color from brown to green – most are glossy to some degree but others are iridescent, as if covered in a fine layer of oil.

These attractive beetles are pests as both immatures and adults. The immature stage, or grub, lives in the soil and feeds on the roots of native grasses and lawns. As such, these grubs can be serious pests of pastures and turf. Yellow or withered vegetation is a sign of feeding damage by the subterranean grubs. The adult beetle feeds on eucalypt leaves (particularly Eucalyptus), and, as such, is very detrimental to eucalypt plantations, but homeowners rarely experience any problems.

As with most beetles, most of the life cycle is spent as a grub in the ground. This stage may last one to two years, depending on the species. Once they’ve grown into big, plump grubs and are ready to transform into adults, they excavate a chamber in the soil and form a cocoon. Then, they develop into an adult and wait for a rain or thunderstorm to soften the soil so they can dig their way to the surface. The adults often emerge together in great numbers, swarming and causing significant damage to eucalypt foliage overnight.

In December, the Christmas beetles are out laying eggs. These eggs will hatch into tiny grubs that will spend their time in the soil during the colder months.

Australian citizens anecdotally report that Christmas beetles have been in decline. They remember vast swarms of these beetles around lights in their childhood but witness so few in current years. Their decline may be linked to growing cities, in which turf and trees and are being replaced by concrete, brick, and asphalt. This may be good for eucalypt growers, but others are saddened to see so few of these beetles buzzing noisily around lights during this festive time of year.

References:
http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/390155/Christmas-Beetles-Coleoptera-Scarabaeidae.pdf
https://australianmuseum.net.au/christmas-beetles
http://www.australiangeographic.com.au/topics/wildlife/2016/11/australias-christmas-beetles