Technology & Science

Native ladybugs lose ground to foreign species

North America is gradually losing its native ladybugs as foreign species introduced decades ago take over.
Sightings of the nine-spotted ladybug, once common in North America, are rare. It's unclear exactly what's led to their decline. (Cornell University/Associated Press)

North America is gradually losing its native ladybugs.

Three once-common domestic species are becoming rare as foreign breeds introduced decades ago — which have different habitats and diets — take over.

Twenty years ago you could find thousands of ladybugs in gardens and near ponds and rivers. Now it's difficult to find any in those environments. 

Cornell University entomologist John Losey said he and his research team find plenty of insects amid the weeds and grass of fields in Ithaca, N.Y., but just not any of the once-plentiful ladybugs species such as the nine-spot.   

"The nine-spot ladybug is declining to the point where we haven't seen it for almost 10 years," Losey said. "It used to be one of the most common ladybugs, all the way from Texas to Canada." 

Another species in decline is the two-spotted ladybug, a carnivorous beetle used to fight infestations of pest insects. A third breed, the transverse ladybug, used to cover the continent but hasn't had a confirmed sighting in Ontario since the 1980s, though it can still be found in the West.

A decade ago, Losey helped launch the Lost Ladybug Project, asking people to become amateur entomologists to help look for ladybugs and send in pictures.

The resulting information was used to create a database of where the different species still exist. They've received more than 12,000 photos from across North America.

Rebecca Rice Smyth, a beetle researcher and the Lost Ladybug Project's co-director of outreach, said the photos are personal, almost affectionate.

"They want to try to help. They think it's an interesting question," she said of the project's civilian contributors. "They like ladybugs."

Ladybugs play a crucial role in controlling garden pests. They eat their weight daily in pests like aphids. While the overall number of them isn't declining in North America, the diversity of species is.

Decades ago the U.S. government brought in several aggressive foreign species for insect control, including the multicoloured Asian ladybug, which was introduced in 1988 from Japan. Another non-native breed that's thriving is the checker spot ladybug, which came from Europe in the 1960s. They appear to be taking over, though it's unclear exactly what's behind the decline in populations of the native insects — it could be competition from foreign bugs, a virus or other environmental factors. 

A lot is at stake, Losey said.

"If some conditions change, and you're dominated by one species and that goes down the tubes, then you could have real problems down the road," he said.

Denis Doucet and his 12-year-old daughter Eleanor go hunting for ladybugs on their farm near Moncton, N.B. They're volunteer bug detectives, documenting every ladybug they find to figure out why they are disappearing.

They're "helping to better understand what's going on with them," Doucet said. "If we don't know where they occur, we don't know how to protect them."

Losey hopes the information will help him determine whether the few native ladybugs still around are heading for extinction and if so, whether they can be saved.