Good Insect, Bad Insect
Local Extension Office Helps Differentiate Between Native & Invasive Species
By Rodger Nichols
Invasive species have been a problem since travel across oceans became possible. Some arrived as stowaways. Others were purposely introduced by well-meaning people but resulted in unexpected consequences, such as rabbits and cane toads in Australia, giant African snails in Florida and starlings in the United States.
In the 1970s, alarms sounded about Africanized bees, dubbed “killer bees,” by the press—with good reason.
In 1956, a researcher in Brazil crossbred the western honey bee (Apis mellifera) with the East African lowland honey bee (Apis mellifera scutellata). The goal was to breed a strain of bees that would produce more honey in tropical conditions.
The sting of the Africanized honey bee is no more potent than any other variety of honey bee, and they do not actively search for humans to attack.
They are more dangerous because they are more easily provoked and quicker to attack in greater numbers. They pursue the perceived threat farther, for as much as a quarter of a mile. They have killed roughly 1,000 humans, with victims receiving 10 times more stings than from European honey bees. They have also killed horses and other animals.
After 26 hives escaped quarantine in 1957, the hybrid expanded north through South and Central America. At its height, the spread was measured at 1 mile a day.
The bees arrived in North America in 1985 and are established from Southern California to Alabama and as far north as southern Utah. Harsher winters and interbreeding with local hives have slowed their progress.
More recently, concern has centered around another flying insect: the Northern giant hornet (Vespa mandarinia). Native to northern Asia, this pest was 1st reported in the Vancouver Island area of Canada in August 2019 and has since been detected in the far northwest corner of Washington.
At 2 inches, it is alarmingly large and has scientists concerned.
Entomology Technician Billy O’Keefe and Entomologist Chris Adams of Wasco County Extension Office explain why these insects are considered so dangerous.
“They wipe out honey bee hives,” Billy says. “That isn’t their only target, but they actually come in and kill all the bees in the hive. The honey bees of China have developed strategies to repulse the hornets, but our native bees are naive to their attacks and get slaughtered.”
Chris points out they are a general predator and eat good and bad bugs.
“But when they locate a honey bee hive, they have the ability to overwhelm the defending workers and lop their heads off,” he says. “They just annihilate the entire hive and then clean it out, eating the larvae.”
That’s not just a concern for beekeepers. Humans rely on pollinator species. Honey bees pollinate 80% of all flowering plants, including more than 130 types of fruits and vegetables.
“When ag specialists in Washington get a sighting of a Northern giant hornet, they have been able to capture one, fit the worker with a miniature radio transmitter and track it back to its nest,” Chris says. “They live in large colonies like yellow jackets. So far they have been able to destroy 4 nests.”
Chris says the hornets are probably no more dangerous to humans than a yellow jacket nest is.
“In the grand scheme of things, I think if you came across a nest you would notice 2-inch wasps coming and going from the nest and be able to avoid it and alert someone,” he says. “People usually encounter yellow jacket nests by accident when they run them over with the lawn mower, for example.
“But these things are gigantic. I don’t think people are going to come into contact with a nest by accident.”
While these insects have not yet been reported in Oregon, news stories in the past few years have people concerned. A native local wasp, the Western cicada killer (Sphecius grandis), is similar in size and coloring, and residents have been reporting them to the extension service.
“It’s a very interesting wasp,” Chris says. “It’s solitary and specializes in cicadas. It will sting and paralyze the cicada, bury it in a ground nest and lay an egg on it so the larva consumes the cicada.”
He says these wasps can be locally abundant. They are most active when everyone is outside working and playing for the summer.
“They’re found near water—ponds or birdbaths or horse troughs,” Chris says.
“They are coming and going looking for water. These wasps come into contact with people in late summer.”
Enough concerned people have contacted the extension office that staff designed a postcard showing the differences between the 2 species.
“Around here, you almost certainly don’t have the invader,” Chris says. “If you check the illustration, the heads are distinctly different. The Northern giant hornet’s is bright yellow, and the native one is duller and much narrower.
“My advice is don’t do anything—unless you have a physical specimen or a really good photograph, and then you can take that to your local extension agent. These native wasps are not dangerous to humans, just cicadas.”
Chris says he and his colleagues are excited by everyone’s enthusiasm and the citizen science approach.
“We also should remember that when we think about invasive species, we are probably giving other countries as many invasive insects as they’re giving us because of global trade,” he says.