Convergent Lady Beetle The word beetle comes from the Anglo-Saxon bitan, meaning to bite, and a sight of the sharp sickle-shaped mandibles of a tiger beetle (Cicindellidae) or the toothed pincer-like jaws of a ground beetle (Carabidae) easily reveals how that name came about. Beetles, formally known as Coleoptera (“shield-wing”, a reference to the glossy sheaths formed by their hardened forewings) outnumber us feeble mammals by a long shot. Current estimates say there are as many as 50 times more species of beetles than of mammals, and that gap widens each year as new beetle species are described. Such diversity—from minuscule (a 0.3 mm featherwing beetle) to huge (a 17 cm Hercules beetle); terrestrial to semi-aquatic and aquatic; plant chewers to meat-eaters; dung movers, corpse recyclers, and more—can lead to mixed feelings about beetles on the part of humans. However, there is one group of beetles that just about everyone loves—the lady beetles (Coccinellidae).
If you live in the USA, you are more likely to refer to lady beetles as ladybugs, but the obsessive taxonomist that lurks within all entomologists compels us to spoil your fun and remind you that “all bugs are insects, but not all insects are bugs”. In the UK, the more whimsical common term of “ladybird” is used, though the mediaeval Christian symbology conferred onto ladybirds provided additional common names such as the evocative but perplexing “God’s little cow”. Lady beetles continue to have a strong hold on modern minds; as a child, I remember an obligation to recite the ditty “ladybug, ladybug, fly away home, your house is on fire, your children are gone”, which with the bloody-mindedness of youth I never questioned (though I did wonder why lady beetles above all others of their kin were so doomed to flaming immolation).
If you live in the USA, you are more likely to refer to lady beetles as ladybugs, but the obsessive taxonomist that lurks within all entomologists compels us to spoil your fun and remind you that “all bugs are insects, but not all insects are bugs”. In the UK, the more whimsical common term of “ladybird” is used, though the mediaeval Christian symbology conferred onto ladybirds provided additional common names such as the evocative but perplexing “God’s little cow”. Lady beetles continue to have a strong hold on modern minds; as a child, I remember an obligation to recite the ditty “ladybug, ladybug, fly away home, your house is on fire, your children are gone”, which with the bloody-mindedness of youth I never questioned (though I did wonder why lady beetles above all others of their kin were so doomed to flaming immolation).
Lady beetles have an advantage in that they are undeniably cute—round and chubby, brightly colored and patterned, they seem hapless and charming as they doodle along in our gardens. They are small enough not to be frightening, and if they do occasionally ooze odorous yellowish fluid from their leg joints upon being handled, what’s a little reflexive bleeding among friends? However, no amount of cuteness will get an insect very far if it isn’t accompanied by some sort of usefulness, and the lady beetle’s sweet appearance is really just a facade, as any aphid will tell you. North America is home to around 500 species of lady beetles, and most are voracious predators on aphids, mealybugs, scale insects, and other soft-bodied insects that plague gardeners and farmers. Lady beetle larvae, which emerge from small clusters of oval orange eggs laid on the undersides of leaves, appear startlingly different than the adults, looking more like tiny orange-and-black alligators covered with warts or branched spines. The larvae feed and grow through four stages (instars) before pupating on leaf surfaces and emerging as adults. Adults often hibernate through the winter in large aggregations in sheltered areas, and it’s not unusual for home gardeners to find a bright cluster of awakening lady beetles underneath a wad of leaf litter in spring.
The ability of lady beetle larvae and adults to consume large numbers of pest insects has given them an exalted status as biological control agents, but unfortunately, their appeal as beneficial insects has also led to the downfall of several of our native species. Many species from other countries have been imported for use as biocontrol agents against crop pests in North America. One of the best-known stories is that of the Vedalia Beetle (Rodolia cardinalis), a coccinellid brought in from Australia in the 1890s to control the cottony-cushion scale insect (Icerya purchasi) that was devastating California’s citrus crops. According to Marshall (2006), 179 species of lady beetle have been imported into North America as biological control agents, and several, along with additional unintentional imports, have become established. In my own garden, the native Convergent Lady Beetle (Hippodamia convergens), so-named for the angled white lines on the pronotum, is outnumbered by the Seven-Spotted Lady Beetle (Coccinella septempunctata), a European import; in the east, this species is thought to have largely ousted the native Nine-spotted Lady Beetle (C. novemnotata). And if there is one lady beetle that everyone loves to hate, it’s the imported Multicolored Asian Lady Beetle (Harmonia axyridis), which varies from pale orange to bight red, with many to no spots, but which can always be distinguished by the blotchy black “M” marking on its white pronotum. The Multicolored Asian Lady Beetle has an unfortunate tendency to invade people’s houses in the fall in search of hibernation sites, where the chemicals they secrete as a defense mechanism stain walls and furniture. During large outbreaks they may feed on and damage fruit crops such as grapes, a very un-lady(beetle)-like behavior, and when their secretions are left on grape skins they can cause an off-flavor in the resulting wine.
The ability of lady beetle larvae and adults to consume large numbers of pest insects has given them an exalted status as biological control agents, but unfortunately, their appeal as beneficial insects has also led to the downfall of several of our native species. Many species from other countries have been imported for use as biocontrol agents against crop pests in North America. One of the best-known stories is that of the Vedalia Beetle (Rodolia cardinalis), a coccinellid brought in from Australia in the 1890s to control the cottony-cushion scale insect (Icerya purchasi) that was devastating California’s citrus crops. According to Marshall (2006), 179 species of lady beetle have been imported into North America as biological control agents, and several, along with additional unintentional imports, have become established. In my own garden, the native Convergent Lady Beetle (Hippodamia convergens), so-named for the angled white lines on the pronotum, is outnumbered by the Seven-Spotted Lady Beetle (Coccinella septempunctata), a European import; in the east, this species is thought to have largely ousted the native Nine-spotted Lady Beetle (C. novemnotata). And if there is one lady beetle that everyone loves to hate, it’s the imported Multicolored Asian Lady Beetle (Harmonia axyridis), which varies from pale orange to bight red, with many to no spots, but which can always be distinguished by the blotchy black “M” marking on its white pronotum. The Multicolored Asian Lady Beetle has an unfortunate tendency to invade people’s houses in the fall in search of hibernation sites, where the chemicals they secrete as a defense mechanism stain walls and furniture. During large outbreaks they may feed on and damage fruit crops such as grapes, a very un-lady(beetle)-like behavior, and when their secretions are left on grape skins they can cause an off-flavor in the resulting wine.
For my own part, when I am giving workshops about beneficial insects to home gardeners, I tell them to rely on the principles of conservation biocontrol, which can be summarized as “if you build it, they will come”, instead of purchasing insects from commercial sources. If you’ve already been noticing lady beetles in your area and would like to become involved in a nation-wide citizen science monitoring program, check out the Lost Ladybug Project . Started in 2000 by entomologists at Cornell University, this kid-friendly, National Science Foundation-funded project collects observations of Coccinellidae from around the country to determine where native and non-native species are found. Photos and information are submitted via an online form, and project scientists confirm (or correct) your species ID. The site features links to multiple identification aids and teaching tools, and you can view submitted records on a map and see what species have been reported near you. With spring well underway in most of the country, there’s no better time than now to get out there and meet the local lady beetles.
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