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Knowing Nature . . .

The Life of a Lady Beetle

July 24, 2007
Jocie Ingram

I've never met anyone who didn't like a lady beetle. These shiny red, black-spotted little beetles are easy to spot climbing up a blade of grass or crossing the surface of a leaf. For centuries lady beetles have been a symbol of good harvests and good weather. Part of this high esteem comes from the fact that they eat aphids, a pest to many crops. In Medieval times, lady beetles rid grapevines of aphid pests and in appreciation were dedicated to "Our Lady".

Beetles are an amazingly large and diverse group, accounting for about 40% of all insects. In fact, there are more kinds of beetles than any other animal on the planet. Lady beetles, in the family Coccinellidae, are prolific too with about 6000 species worldwide. Of these, there are about 480 species in North America, and 95 in BC.

Asian Lady Beetle photo © Dave Ingram Lady Beetle Larva photo © Dave Ingram

Lady beetles have a head with two eyes and antennae. Right behind the head is a black and white patterned shield called a pronotum that protects the neck from predators. Brightly patterned wing coverings, or elytra, protect the main body of the lady beetle. If you watch a lady beetle take flight you will see the wing coverings part revealing two lacy, transparent wings as the bug hovers off. Like most insects, lady beetles have 6 legs.

Lady beetle life begins with a cluster of yellow eggs, laid on the underside of a leaf. After four or five days the eggs hatch into larvae, which are long and dark with banded red patterning, and look like "spiky accordions with legs". The larvae feed voraciously on aphids for 4 or 5 weeks, and shed 3 times prior to turning into pupae. After about 10 days they emerge as adult lady beetles. It takes about 24 hours for the lady beetle to develop its characteristic spots. In BC, there are typically 2-3 generations of lady beetles per year. In its lifetime a lady beetle will consume about 2000 aphids, and may also feed on mites and scale insects.

Towards late summer, large swarms of adult lady beetles will seek a spot to hibernate. They have been known to hibernate beneath leafy debris on the ground, rocky mountaintops, and in buildings. In the spring, the over wintered adults will come out of hibernation and reproduce, started the cycle over again.

Lady beetles have long been used as a pest control. Since the 1880's, more than 170 species of lady beetle have been introduced to North America. There is concern that some of these introduced species are out competing native species. One of the most invasive is the Asian lady beetle (Harmonia axyridis), which is native to Japan, Korea and other parts of Asia. This beetle is orangey-red and typically has 19 spots and a black "M" pattern on the pronotum.

Doing a quick reconnaissance, I found several Asian lady beetles on my own property. With names like "two-spotted lady beetle" and "seven-spotted lady beetle" lady beetle identification should be easy, but unfortunately things such as the number of spots can be variable. The two-spotted sometimes has four spots, and the Asian lady beetle comes in several colour forms, including a spotless form. Several factors have to be taken into account apart from spots such as the shade of red (orange or apple-red), the patterning on the pronotum, and the overall shape of the beetle (some are longer, others more round).

"The Bug Lady", Jessica Dawe, runs a biological control company that operates out of Langley, BC. Lady beetles are great helpers in keeping aphids under control, and are an effective way to avoid the use of pesticides. This year, The Bug Lady has given presentations at both Seedy Saturday, and at the Comox Valley Seed Savers demonstration garden next to the Farmer's Market. Earlier this spring, there was an exciting lady beetle release at the garden, and the public was offered a bag of lady beetles to take home. The Bug Lady uses a native species of lady beetle, the Convergent lady beetle (Hippodamia convergens). This species is quite elongate, and has 12 spots (can vary!) and two converging white stripes that outline the black pronotum. To order lady beetles, or find out more about other biological controls, check The Bug Lady's website

It is little wonder that lady beetles have such a good rapport with humans. These little beetles, regarded as cute by many, cheer us with their bright red and black patterns. Though pretty to look at, they are one of many beneficial insects that seem to work in partnership with us against pests.