Thursday, July 26, 2012
Seven-Spotted Lady Beetle
Seven-spotted lady beetles (Coccinella septempunctata) are one of the most common ladybugs found in Europe. It was apparently intentionally introduced to the United States on several occasions from 1954 to 1971 to help control aphid populations and each one of these attempts failed. Ironically a successful, accidental introduction was discovered in New Jersey in 1973. They have since established themselves throughout much of North America and often out compete native species of lady beetles for available food sources. In their native home of Europe they are however facing trouble as the non-native Harlequin Ladybird Beetle out competes it.
Even though this insect is not native to North America it has established itself in such a way that it is considered naturalized and many states have adopted it as their state insect, including New Hampshire, Delaware, Tennessee, Pennsylvania, Ohio, and Massachusetts. This species occurs throughout Missouri and is quite common in some locations.
Their bright red color is aposematic in nature and is designed to ward would-be predators that they taste bad. They are able to produce a foul tasting secretion that they emit from their legs. These are large lady beetles and may reach lengths up to 1/4 of an inch. In addition to being a bright red, they have three black spots on each wing and a single spot located on the median line near the back of the head. This gives them a total of seven spots from which they get their common name.
Reproduction takes place in the spring, females will lay clusters of eggs near aphid colonies. When the eggs hatch the newly born lady beetle larvae will have a ready food supply. It takes them several weeks to reach adulthood.
Even though these insects are not native and do compete with native species for available food, they are beneficial because of their voracious appetite for aphids and other soft bodied insects that will damage your veggies and other garden favorites, not to mention your prized roses.