ARTHROPOD MUSEUM NOTES

Number 76 • April 6, 2010 • Jeffrey K. Barnes


Nine-spotted lady beetle
Order: Coleoptera
Family: Coccinellidae
Genus and species: Coccinella novemnotata Herbst

Nine-spotted lady beetle Nine-spotted lady beetle

Ladybugs, also known as lady beetles or ladybird beetles, comprise nearly 500 species in the United States and Canada and several thousand species worldwide. Old superstitions and folklore told of lady beetles as harbingers of fine weather, bountiful harvest, and good romance. They were revered for their role in ridding crops of aphids, scales, and other insect pests, and it was considered unlucky to kill them.  The nine-spotted lady beetle is about one quarter of an inch long and bears nine black spots that can be seem looking at the beetle from above—four spots on each wing cover and one forward spot on the central scutellar triangle and following areas of the two wing covers. A female produces up to about a thousand eggs. Individuals develop from egg to adult in two to four weeks, adults live two to four months, and the species has one or two generations each year. Both adults and larvae feed on aphids and other small, soft-bodied insects. Adults consume hundreds of aphids each day, and when abundant the species is an important biological control agent for pest aphids. Only 25 years ago the nine-spotted lady beetle was considered one of the most widespread and common lady beetles in North American north of Mexico. Its range stretched across the continent from Maine to Florida west to British Columbia and southern California. Unfortunately, the species has undergone a severe decline in recent years, and few if any individuals have been found in most states. The last time it was found in most northeastern states was in the late 1980’s and early 1990’s, although in 2006 one specimen was collected in Virginia – the first individual collected in eastern North America in over fourteen years and only the seventh known to be collected anywhere in North America in a decade. However, a 2007 report indicated that this species survived in sparsely vegetated portions of sand dunes and badland pediment slopes, and in 2008 twelve individuals were detected at several sites with similar habitat in western South Dakota and Nebraska. The last specimen deposited in the University of Arkansas Arthropod Museum is dated November 1976. It appears that this once widespread and dominant species has been consigned to marginal habitats. The causes of the decline are unclear, but several possibilities have been postulated, including competition from introduced lady beetles, changes in land-use and cropping patterns, decline in aphid densities, parasitism, disease, or even global climate change.