Friday, January 15, 2010
Spotted Lady Beetle
Name: The Spotted Lady Beetle is Coleomegilla maculata. It is in the family Coccinellidae along with around 480 other species of lady beetles found in North America. The “lady” in the name is reputed to be the Virgin Mary. One of the stories is that in the middle ages farmers, who were suffering crop losses from a devastating infestation of aphids, prayed to Mary and received relief in the form of aphid-eating beetles which then became known as “Our Lady’s beetles.” Today, lady beetles, ladybugs, and ladybirds (regardless of their moniker) are among the more well known insects.
Spots: To most of us, it would seem redundant to add “spotted” to the name of these familiar beetles but there are species that have no spots at all. Among the spotted species, some are named for the number of their spots – for example, the two-spotted, seven-spotted, nine-spotted, 14-spotted and 20-spotted. The two-spotted species is the typical orange color with two black spots but there is another species with two spots. It is a black beetle with two red spots and goes by the vivid name of “twice-stabbed lady beetle.” Within any given spotted species, like the common Asian Ladybug that comes into houses in the fall, there can be a lot of variation in color and markings.
Native and introduced lady beetles: Lady beetles are insect predators and for that reason some species have been deliberately introduced from other countries to combat crop pests. The first recognized instance of using a “foreign“ insect to prey on a pest insect dates back to 1888 when the Vedalia Lady Beetle was brought into California from Australia to take care of cottony cushion scale in citrus groves. This was followed in 1892 by the Mealybug Destroyer, another Australian lady beetle which preyed on a different citrus pest. These programs were deemed successful and were followed by the introduction of the Asian Lady Beetle at various times in the 20th century to take care of aphids in apple and pecan orchards. The Spotted Lady Beetle is one of our native species. Its diet is split between pollen and aphids. If you buy lady beetles from a garden supply store, you are likely to get the Convergent Lady Beetle, another native species. You are also likely to be doing a nice favor for your neighbors.
When and where found: Lady beetles hibernate and since the Spotted Lady Beetle is a native, it has found places in nature – not in our homes like the Asian Lady Beetle – to find shelter for the winter. I found this one in a bald-faced hornet nest recently removed by friends from the eaves of their house. (I am very happy to have friends who know I would welcome such a gift.) This particular nest had 11 layers of paper which provided insulation from summer heat for the hornet hive in the center of the nest. By winter, when the hornets are either dead or gone, other insects have moved in to use the nest for protection from the cold. Depending on what I stumble on for next week’s topic, I may continue with the story of this nest and another of its inhabitants.
Distinguishing characteristics: The Spotted Lady Beetle is sometimes more pinkish than orange and is therefore also known as the Pink Spotted Lady Beetle. It has a predictable number of black spots – two on the thorax and six on each of the wing covers. This one was more of the orange variety and, as you can tell from the photo, its body shape is a narrower oval than that of the Asian Lady Beetle.
Sources: My favorite insect guide book, the Kaufman Field Guide to Insects of North America by Eric R. Eaton and Kenn Kaufman; website at www.lostladybug.org. ∆
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