When you’re scouting your fields this summer, keep an eye out for ladybugs. If you spot some, pull out your cell phone and snap a quick photo. You’ll help entomologists understand what is happening to native ladybugs, and why several formerly abundant species have suddenly become rare.
The Lost Ladybug Project is charting ladybug populations across the U.S., with the help of 4-H clubs, students, gardeners and more than 3,000 others. Since the informal survey began three years ago, 10,000 ladybug digital images have been sent in from all over the country, says Cornell University Extension Entomologist John Losey, program founder. Farmers and crop scouts are in an ideal position to report on which ladybug species are thriving in cropland habitat, Losey says.
Why should you give a hoot about ladybugs?
For starters, they have voracious appetites for insect pests. One ladybug may eat 5,000 aphids. They also feed on spider mites and the eggs of corn borers, corn earworms, fall armyworms and many other damaging pests. That reduces the need for insecticides to protect crops.
“Lady beetles are so important for controlling pests,” Losey says. “We want to get a handle on what population shifts are taking place, and what that will mean for agriculture.”
Before about 1985, 98% of ladybugs in this country were natives, Losey says. Today, it’s fewer than 70%.
Three native species have all but vanished in the last 25 years, says Louis Hesler, an entomologist at the USDA Agricultural Research Laboratory in Brookings, SD. The nine-spotted ladybug, the two-spotted ladybug and the transverse ladybug were once common in farm fields across the U.S., but are rarely seen these days. Meanwhile, populations of foreign species, such as Asian ladybugs and seven-spotted ladybugs, have exploded. “We are concerned.” Hesler says. “What has changed? We don’t have answers.”
Still, don’t foreign ladybugs devour crop pests the same as natives?
Certainly, Hesler says. Seven-spotted ladybugs, for instance, were introduced intentionally to feed on pea aphids. Likewise, multicolored Asian ladybugs were brought to this country to help control pecan aphids in the Southeastern U.S. Both types have become major predators of soybean aphids.
In fact, “The total number of ladybugs may not have declined,” Losey says. However, “We’ve gone to a less diverse mix of species dominated by foreign ladybugs.” That weakens biological pest control. “In general, you get the best pest suppression with a diverse group of species that includes natives.”
What happened to the ladybugs?
So what happened to the lost ladybugs?
“We don’t know yet,” Losey says. Perhaps they were crowded out of their traditional habitat by more competitive invaders, although native numbers had started to shrink before the foreigners took over. “Did the natives decline and then the foreigners moved into the void? Or did the foreigners move in and push the natives out?”
The natives may have shifted their habitat from farm fields to woods or grasslands, Hesler says. Or, they might be moving west into drier regions. He has found nine-spotted, two-spotted and transverse ladybugs in western South Dakota and western Nebraska. They’ve been spotted in Colorado, Oregon and Washington, too.
Once entomologists have a clearer understanding of ladybug population patterns, they may try re-establishing colonies of natives in Midwest farm fields, Hesler says. Meanwhile, all you shutterbugs can help Losey and Hesler track ladybugs.
“We ask for photos, because you can identify ladybugs from their spots alone,” Losey says. The scientists are interested in a digital picture of any ladybug you find, even if it’s not a native. That will help them gauge the relative abundance of species. And if you can send photos from the same fields over time, the information becomes more valuable yet.
Thanks to a growing team of citizen scientists, Losey says, “We have a better handle on what species are out there, in what habitats, and where the natives are hanging on.”
For instructions on how to participate in the Lost Ladybug Project, plus general ladybug information go to www.lostladybug.org .
• Ladybugs aren’t true bugs, but members of the beetle order Coleoptera. We call them ladybugs anyway. Other common names are lady beetles, ladybirds or ladybird beetles.
• Ladybugs prey on aphids and other soft-sided insects, including scale insects, mealybugs, spider mites and eggs of the European corn borer.
• There are nearly 500 ladybug species native to North America.
• Three once-common native ladybug species have disappeared from U.S. farm fields in the last 20 years: nine-spotted, two-spotted and transverse ladybugs.
• Adult ladybugs live about a year.
• Ladybugs’ bright colors and spots serve as a warning to predators that the beetles taste badly.
• According to legend, ladybugs got their name during the Middle Ages, when swarms of aphids destroyed crops. Farmers prayed to the Virgin Mary for help, which came in the form of colorful ladybugs that devoured the aphids. The farmers named the insects “Our Lady’s beetles.”
Source: Lost Ladybug Project, www.lostladybug.org