October 27, 2016
Green lacewing larva disguised as a tiny lint ball, walking up our den wall. Photo by: Martin Schlageter
The other night, as I was walking through the house turning out lights and locking up, I saw a weird, tiny ball of debris—the kind of thing you see in the corner of a house that has multiple pets and an idle vacuum cleaner—making its way up the wall. I called for my husband and said, “What in the world is going on? Does that dust bunny have legs?”
For the next 20 minutes we watched it slowly traverse our wall and tried to capture photographs of it on our small point-and-shoot, hoping to get a closer look on the computer (blurry photo above). The next day my husband submitted a couple of photos of it to iNaturalist and received a prompt answer: green lacewing larva.
Lacewings are beneficial insects in the garden. Their larvae are voracious predators called aphid lions, as aphids are a preferred meal. They also eat a number of other soft-bodied insects, like mealybugs and immature whiteflies, that are considered garden pests. I am always gratified to find their distinctive eggs—individually laid on a minuscule silken stalk—on plants in my garden. It's not unusual to find adult lacewings at night near a porch light, to which they are attracted.
Their larvae look like little alligators, with ferocious sickle-shaped mandibles that are used to capture prey. What my husband and I didn't know was that the larvae also use debris, including the corpses of their victims, to camouflage themselves from both predators and prey. Amazingly, that behavior dates back to the early-to-mid Cretaceous period, about 130 million years ago.
Green lacewing larva eating whitefly nymphs. Photo by: Jack Dykinga, courtesy of U.S. Department of Agriculture
Earlier this year, an international team of researchers published a study in which they examined 35 insects, including lacewing relatives, preserved in amber from Myanmar, Lebanon, and France. The researchers were astonished to find the broad range of camouflage already used by insects in the Cretaceous.
"It is very surprising how early in evolution such complex insect behavior developed: The larvae had to search actively for suitable 'camouflage material,' pick it up, and cloak themselves with it," said Dr. Bo Wang, who led the research team, in the study's press release. Dr. Jes Rust, a paleobiologist at the University of Bonn, which participated in the study, explained that camouflage, with its distinct advantages, was 'invented' multiple times in different insect species during evolution.
My husband gently captured the wondrous little ball of lint and took it outside, where we hope it will continue its valued work in our garden.