5 vital roles insects play in our ecosystem

As insect populations plummet, scientists show what the world would lose if bugs disappear.

This story appears in the May 2020 issue of National Geographic magazine.

Insects may sting or startle us, but they help keep the planet livable. As some insect populations plummet, scientists are scrambling to understand why—is it climate change, pesticides, loss of habitat to farms and cities?—and to identify some of the many unknown species before they’re gone.

Five crucial insect jobs

Every buzzing, crawling, and hovering insect is a cog in an ecological machine. Tiny, individual efforts add up to colossal benefits for life on Earth.

A pair of blue tits might collect up to 100 caterpillars every day to feed a single chick.

Eurasian blue tit

(Cyanistes caeruleus)

Winter moth caterpillar

(Operophtera brumata)

PROVIDERS

Insects are in nearly every food chain. Many larger animals—birds, bats, amphibians, and fish—eat insects before they in turn are eaten by predators. The dearth of insects is suspected to be a leading cause of recent declines in bird populations.

WHAT COULD HAPPEN IN A WORLD WITHOUT INSECTS

Species that are higher up the food chain suffer population losses.

Dung beetles feed on and help decompose the dung of grazers.

Dung beetle

(Canthon imitator)

DECOMPOSERS

Waste-eating insects unlock nutrients for use by the ecosystem that would otherwise stagnate in dung, dead plants, and carrion. Dung beetles process parasite- breeding and grass-killing cattle dung in 23 months versus the 28 it would otherwise take.

Waste and carrion persist in ecosystems, impeding the flow of nutrients.

The damsel bugs in an acre of cropland can eat a million aphids a day.

Damsel bug

(Nabis americoferus)

Aphids

(Acyrthosiphon pisum)

PEST CONTROLLERS

By feeding on crop-threatening pests, predatory insects perform the role of pesticides without chemicals. This cuts pest-control costs and increases yields, saving agricultural industries billions of dollars every year—while reducing toxic pesticide residue on crops.

Waste and carrion persist in ecosystems, impeding the flow of nutrients.

A bumblebee can visit (and help pollinate) 3,000 flowers a day.

Rusty patched bumblebee

(Bombus affinis)

POLLINATORS

Nearly 90 percent of flowering plant species and 75 percent of crop plant species depend on pollination by animals—mostly insects. Overall, one out of every three bites of food humans eat relies on animal pollination in the production process.

Crops can’t reproduce; humans and animals lose key food sources.

One termite colony can excavate a quarter ton of soil every year.

Termites

(Macrotermes natalensis)

SOIL ENGINEERS

Termites (and ants) can trans- form soil in hot, dry climates. Their tunneling aerates hard ground, helping it retain water and adding nutrients. In some regions, the introduction of termites has turned infertile land into cropland within a year.

Soils in arid regions become barren, crops fail, and deserts expand.

Species in five major orders of insects have experienced population losses. Of the 2,200 species tracked for population trends by the International Union for Conservation of Nature—a tiny sample of what’s out there—nearly half face declining numbers.

Population is:

Decreasing

Stable

Increasing

27%

71%

of

species

2%

Dragonflies

and damselflies

Odonata

ORDER

63

36

1

Butterflies and moths

Lepidoptera

42

57

1

Bees, wasps, and ants

Hymenoptera

61

37

2

Beetles

Coleoptera

12

85

3

Grasshoppers and crickets

Orthoptera

MANUEL CANALES AND TAYLOR MAGGIACOMO; NGM STAFF; SCOTT ELDER. ART: DANIEL SOLANO. SOURCES: SCOTT BLACK AND MATTHEW SHEPHERD, XERCES SOCIETY FOR INVERTEBRATE CONSERVATION. INSECT SPECIES TRENDS: IUCN RED LIST OF THREATENED SPECIES; GRAPHIC ADAPTED FROM RODOLFO DIRZO, SCIENCE, 2014. SPECIES NUMBERS: BRETT SCHEFFERS, TRENDS IN ECOLOGY & EVOLUTION, 2012

Five crucial insect jobs

Every buzzing, crawling, and hovering insect is a cog in an ecological machine. Tiny, individual efforts add up to colossal benefits for life on Earth.

A pair of blue tits might collect up to 100 caterpillars every day to feed a single chick.

Eurasian blue tit

(Cyanistes caeruleus)

Winter moth caterpillar

(Operophtera brumata)

PROVIDERS

Insects are in nearly every food chain. Many larger animals—birds, bats, amphibians, and fish—eat insects before they in turn are eaten by predators. The death of insects is suspected to be a leading cause of recent declines in bird populations.

Species that are higher up the food chain suffer population losses.

WHAT COULD HAPPEN IN A WORLD WITHOUT INSECTS

Dung beetles feed on and help decompose the dung of grazers.

Dung beetle

(Canthon imitator)

DECOMPOSERS

Waste-eating insects unlock nutrients for use by the ecosystem that would otherwise stagnate in dung, dead plants, and carrion. Dung beetles process parasite- breeding and grass-killing cattle dung in 23 months versus the 28 it would otherwise take.

Waste and carrion persist in ecosystems, impeding the flow of nutrients.

WITHOUT INSECTS

The damsel bugs in an acre of cropland can eat a million aphids a day.

Damsel bug

(Nabis americoferus)

Aphids

(Acyrthosiphon pisum)

PEST CONTROLLERS

By feeding on crop-threatening pests, predatory insects perform the role of pesticides without chemicals. This cuts pest-control costs and increases yields, saving agricultural industries billions of dollars every year—while reducing toxic pesticide residue on crops.

Pests proliferate, damaging crops and forests, spurring increased pesticide use.

WITHOUT INSECTS

Rusty patched bumblebee

(Bombus affinis)

A bumblebee can visit (and help pollinate) 3,000 flowers a day.

POLLINATORS

Nearly 90 percent of flowering plant species and 75 percent of crop plant species depend on pollination by animals—mostly insects. Overall, one out of every three bites of food humans eat relies on animal pollination in the production process.

Crops can’t reproduce; humans and animals lose key food sources.

WITHOUT INSECTS

One termite colony can excavate a quarter ton of soil every year.

Termites

(Macrotermes natalensis)

SOIL ENGINEERS

Termites (and ants) can transform soil in hot, dry climates. Their tunneling aerates hard ground, helping it retain water and adding nutrients. In some regions, the introduction of termites has turned infertile land into cropland within a year.

Soils in arid regions become barren, crops fail, and deserts expand.

WITHOUT INSECTS

Species in five major orders of insects have experienced population losses. Of the 2,200 species tracked for population trends by the International Union for Conservation of Nature—a tiny sample of what’s out there—nearly half face declining numbers.

Odonata

Lepidoptera

Hymenoptera

Coleoptera

Orthoptera

ORDER

Dragonflies

and damselflies

Grasshoppers and crickets

Beetles

Butterflies and moths

Bees, wasps, and ants

27%

12

71%

of

species

61

42

63

57

37

85

36

2%

1

1

3

2

Decreasing

Stable

Increasing

Population is

MANUEL CANALES AND TAYLOR MAGGIACOMO; NGM STAFF; SCOTT ELDER. ART: DANIEL SOLANO. SOURCES: SCOTT BLACK AND MATTHEW SHEPHERD, XERCES SOCIETY FOR INVERTEBRATE CONSERVATION. INSECT SPECIES TRENDS: IUCN RED LIST OF THREATENED SPECIES; GRAPHIC ADAPTED FROM RODOLFO DIRZO, SCIENCE, 2014. SPECIES NUMBERS: BRETT SCHEFFERS, TRENDS IN ECOLOGY & EVOLUTION, 2012

Five crucial insect jobs

Every buzzing, crawling, and hovering insect is a cog in an ecological machine. Tiny, individual efforts add up to colossal benefits for life on Earth.

A pair of blue tits might collect up to 100 caterpillars every day to feed a single chick.

Eurasian blue tit

(Cyanistes caeruleus)

Winter moth caterpillar

(Operophtera brumata)

PROVIDERS

Insects are in nearly every food chain. Many larger animals—birds, bats, amphibians, and fish—eat insects before they in turn are eaten by predators. The death of insects is suspected to be a leading cause of recent declines in bird populations.

Species that are higher up the food chain suffer population losses.

WHAT COULD HAPPEN IN A WORLD WITHOUT INSECTS

Dung beetles feed on and help decompose the dung of grazers.

Dung beetle

(Canthon imitator)

DECOMPOSERS

Waste-eating insects unlock nutrients for use by the ecosystem that would otherwise stagnate in dung, dead plants, and carrion. Dung beetles process parasite- breeding and grass-killing cattle dung in 23 months versus the 28 it would otherwise take.

Waste and carrion persist in ecosystems, impeding the flow of nutrients.

WITHOUT INSECTS

The damsel bugs in an acre of cropland can eat a million aphids a day.

Damsel bug

(Nabis americoferus)

Aphids

(Acyrthosiphon pisum)

PEST CONTROLLERS

By feeding on crop-threatening pests, predatory insects perform the role of pesticides without chemicals. This cuts pest-control costs and increases yields, saving agricultural industries billions of dollars every year—while reducing toxic pesticide residue on crops.

Pests proliferate, damaging crops and forests, spurring increased pesticide use.

WITHOUT INSECTS

Rusty patched bumblebee

(Bombus affinis)

A bumblebee can visit (and help pollinate) 3,000 flowers a day.

POLLINATORS

Nearly 90 percent of flowering plant species and 75 percent of crop plant species depend on pollination by animals—mostly insects. Overall, one out of every three bites of food humans eat relies on animal pollination in the production process.

Crops can’t reproduce; humans and animals lose key food sources.

WITHOUT INSECTS

One termite colony can excavate a quarter ton of soil every year.

Termites

(Macrotermes natalensis)

SOIL ENGINEERS

Termites (and ants) can transform soil in hot, dry climates. Their tunneling aerates hard ground, helping it retain water and adding nutrients. In some regions, the introduction of termites has turned infertile land into cropland within a year.

Soils in arid regions become barren, crops fail, and deserts expand.

WITHOUT INSECTS

Species in five major orders of insects have experienced population losses. Of the 2,200 species tracked for population trends by the International Union for Conservation of Nature—a tiny sample of what’s out there—nearly half face declining numbers.

Odonata

Lepidoptera

Hymenoptera

Coleoptera

Orthoptera

ORDER

Dragonflies

and damselflies

Grasshoppers and crickets

Butterflies and moths

Bees, wasps, and ants

Beetles

27%

12

71%

of

species

61

42

63

57

37

85

36

2%

1

1

3

2

Decreasing

Stable

Increasing

Population is

MANUEL CANALES AND TAYLOR MAGGIACOMO; NGM STAFF; SCOTT ELDER. ART: DANIEL SOLANO. SOURCES: SCOTT BLACK AND MATTHEW SHEPHERD, XERCES SOCIETY FOR INVERTEBRATE CONSERVATION. INSECT SPECIES TRENDS: IUCN RED LIST OF THREATENED SPECIES; GRAPHIC ADAPTED FROM RODOLFO DIRZO, SCIENCE, 2014. SPECIES NUMBERS: BRETT SCHEFFERS, TRENDS IN ECOLOGY & EVOLUTION, 2012