There has been a great deal of excitement in Our Evergreen World this week, all due to a big concentration of ladybird beetles in Genesee Park.
This is a phenomenon that occurs every few years — or perhaps it occurs every year but is sometimes where no one notices it. I have seen it three times on Bear Mountain. Little seems to be known about why they do this, but some scientists believe it is a form of aestivation that some animals do to avoid extreme heat. Some of the ground squirrels go into their burrows and enter a torpid state during very hot weather (aestivation) and then return to an active life when cooler weather comes before they enter the state of hibernation for the winter.
Some years ago I wrote about a gathering of ladybird beetles, at that time, as they have this year, they had swarmed into the mountains to escape the heat. If that is true, then they should return to the plains for the rest of the summer and then congregate again in the fall, for this seems to be their normal way to escape winter’s cold temperatures. They gather by the thousands in September or October in places where they can crawl under rocks, into crannies and crevices, beneath pine needles and other duff of the forest floor. Here, they go into complete hibernation for about five months. They are totally inactive until the March sunshine melts the snow enough to bring them out of hibernation. Eventually the huge numbers disperse as they fly off to lay their eggs, feed and live somewhere else.
Both adult and larval ladybird beetles eat aphids, and this has earned them the respect and protection of gardeners and farmers around the world. At one time the orange groves of California were threatened by Australian cushion scale that had accidentally escaped in our country. When all else failed, they sent to Australia for the ladybugs that eat scale insects there. This worked remarkably well and was the beginning of using biological controls in this country. Others are now being imported in hopes of stopping the hemlock wooly adelgids that are slowly killing all the hemlocks in the Eastern states.
Lady beetles are found all around the world, with the exception of the permanently snow-covered parts of the Arctic and Antarctic; they adapt quickly to changes in habitat and weather, so there are about 5,200 known species in the world and 50 or more in Colorado. The convergent ladybug is probably the most common in our area. They are known by their red elytra (wing covers) with black spots. Most lady beetles have red elytra with black spots, which can vary in number from two to many. It is believed that the black spots are a form of protection, for they look like eyes to their enemies and deter them long enough for the beetles to take wing and fly away.
“Ladybug” has become the common name, but it is not a very accurate one, for they are not true bugs. To an entomologist, “bugs” are an order of insects, “Hemiptera,” which have a leathery base to their wings and a long, tube-like mouth for sucking. Beetles have stiff wing covers and transparent wings that they use to fly. In the Middle Ages, beetles were dedicated to the Virgin Mary, hence the names “Our Lady’s bird” or Our Lady’s bug.” These just were shortened to “ladybug” because it was easier to say, and to the amateur most all insects are just “bugs.” The childhood ditty of “Ladybug, ladybug, fly away home, Your house is in fire, Your Children will burn” came from the European custom of pruning grape vineyards and piling the pruned vines at the end of each row. Often there were ladybugs on the branches, or others flew in to hibernate beneath the piles over winter. When the piles were burned in early spring, the ladybugs were seen flying out; thus, the childhood song was born.
Female ladybugs lay clusters of bright yellow eggs on the underside of leaves on which the larva feed. These eggs hatch in five to eight days, becoming larvae that live for about three weeks before they change into a pupa that becomes the adult. They may have as many as three or four broods per year, depending upon the weather. Their life span is about one year. It has been estimated that a single ladybug during her life as a larva and an adult will eat as many as 8,000 aphids.
At times when they congregate, especially in California, local people collect ladybugs in great quantities to sell to nurseries. The nurseries in turn package them and sell them to gardeners and farmers who want them for aphid control; the only problem with this is, unless they find their favorite food immediately when released, they tend to fly away to search for food, and your expensive ladybugs are gone — perhaps to eat the aphids in your neighbor’s garden.