Insects Up High

Deep in the Amazon rainforest, 37 miles north of Manaus, Brazil, stands a giant metal tower. Stretching 151 feet high, it rises through the rainforest canopy. Its spire reaches even higher above the treetops.

The tower, called ZF-2, was built in the 1980s to study climate. But recently, a team of entomologists climbed to its top to study something different: bugs!

From beetles to crickets to leaf-cutter ants, the insects lurking on the ground of the Amazon rainforest have been studied before. But an international team led by José Albertino Rafael, an entomologist from Brazil’s National Institute of Amazonian Research, wanted to know which insects live in the canopy. The team spent two weeks in 2017 collecting, counting, and sorting all the bugs they could catch. They found ants, bees, wasps, moths, butterflies, beetles, and flies—so many flies.

The insects were so abundant at all elevations on the tower that the team started thinking of the rainforest as not just a horizontal ecosystem but a vertical one. Tropical rainforests are already known to be ecosystems with high biodiversity, or variety of life. More than 30 percent of the world’s estimated species of animals, plants, and insects live there! But not even the world’s foremost bug experts could have anticipated just how many insects call the rainforest’s canopy home.

“I’ve seen insect samples from a lot of places in the Amazon. This was really something special,” says Brian Brown, an entomologist—and fly expert—at the Natural History Museum of Los Angeles County, who was a part of the team.

Deep in the Amazon rainforest stands a giant metal tower. It stretches 151 feet high, not including the spire on top. That’s even higher than the rainforest canopy—the thick layer at the tops of the trees.

The tower is called ZF-2. It’s 37 miles north of Manaus, Brazil. It was built in the 1980s to study the climate. But recently, a team of scientists climbed it for another reason. They were looking for bugs! 

Insects like beetles, crickets, and leaf-cutter ants lurk on the ground in the Amazon. But an international team of entomologists, or insect scientists, wanted to know which insects live up top. Instead of trying to climb the trees, they studied bugs at different levels of the tower. They spent two weeks in 2017 collecting and counting all the insects they could catch. The team found ants, bees, wasps, moths, butterflies, and beetles. They also found flies—a lot of flies.

The expedition was led by José Albertino Rafael. He’s an entomologist from the National Institute of Amazonian Research in Brazil. He and his colleagues already knew that tropical rainforests are hot spots for biodiversity, or variety of life. It’s estimated that more than 30 percent of the world’s animal and plant species live there! The scientists also knew that many of those animal species were insects. But even they hadn’t predicted how many bugs call the rainforest canopy home.

“I’ve seen insect samples from a lot of places in the Amazon. This was really something special,” says Brian Brown. He’s an entomologist at the Natural History Museum of Los Angeles County who was a part of the team.

With a total of five platforms at roughly 26-foot intervals, the ZF-2 tower proved to be the perfect tool for a vertical investigation. “When you’re up on top of the tower, there’s unbroken forest as far as you can see,” says Brown.

On the ground level, the team was able to collect all the familiar bugs they’d been studying throughout their careers. But when they stretched out their 20-foot-long netted traps at the next four levels—at heights of 26 feet, 52 feet, 79 feet, and 105 feet—they discovered what buggy secrets the canopy had in store. And boy, were there secrets!

How many insects did the team collect when all was said and done? According to their study published earlier this year, they recorded 37,778 individual specimens. Of those, an astonishing 69 percent were found above ground level.

That’s a lot of bugs! The raw number of individual insects they counted over that two-week period impressed the team. But it was the variety, or richness, of species at every level that bowled them over. Not only was there greater species richness throughout every above-ground level than the team had anticipated but the majority of the specimens they collected are likely to be new species altogether.

“I’ve looked through canopy samples from other places, and they just didn’t have that many flies,” Brown says. “But then when I started looking through some of the ZF-2 samples, I realized there’s all kinds of really cool stuff in here. Things I’ve never seen before!”

The ZF-2 tower has five platforms. They’re positioned about every 26 feet on the way up. That made the tower the perfect tool for investigating bugs living in the canopy. “When you’re up on top of the tower, there’s unbroken forest as far as you can see,” says Brown.

The team used long netted traps to collect insects at each level. On the ground level, they found a lot of familiar bugs. They and other scientists had been studying these insects throughout their careers. But at the next four levels—at heights of 26 feet, 52 feet, 79 feet, and 105 feet—they started to find new and exciting things.

All in all, the team collected 37,778 individual insects. Of those, an astonishing 69 percent were above ground level. The sheer number of bugs they found impressed the entomologists. But it was the variety of species that really bowled them over. At every level above the ground, they found more biodiversity than they had anticipated. And most of the specimens they collected are likely previously unknown species!

Brown, who is a fly expert, was particularly excited. “I’ve looked through canopy samples from other places, and they just didn’t have that many flies,” he says. But “there’s all kinds of really cool stuff in [the ZF-2 samples]. Things I’ve never seen before!”