Surveys in Europe and North America show a dramatic decline in the number of bugs buzzing around. Although global data are missing, many researchers are convinced that this environmental disaster is happening worldwide.
Image: Colourbox
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Insects can sting, bite and carry diseases. Some of us would be happy if there weren't any mosquitoes, horseflies and cockroaches left to bother us.
But what about butterflies and bumblebees? Wouldn't we miss them if they were gone?
Conservationists have been voicing their concern that all insects — including those that we love so much — are slipping away.
"In the summer, there were hundreds of butterflies, especially monarch butterflies, where I grew up," Scott Black, executive director of the Xerces Society for Invertebrate Conservation in Portland, Oregon, tells DW. "Now, you're lucky to find a dozen."
Black also points to the "windshield phenomenon": you don't have to clean your car's windshield as often as you did in the past — there aren't as many smashed insects to scrape off.
Black, like other conservationists, believes this is an indication of a global insect die-off: "You just don't see those insects anymore."
"And I believe this is happening around the world."
Insects are closely connected to plants, water and soils — which is why they suffer the most from intensive agricultureImage: picture-alliance/Arco Images/W. Rolfes
A tough nut to crack
For scientists, personal observations like the effort put into windshield cleanup don't cut it as proof that the overall number of insects is indeed declining.
Kees Booij, an ecologist at the University of Wageningen in the Netherlands, even suggests that the notion of a worldwide insect die-off is simply based on "rumors and claims which are not supported by publications."
"Things are certainly not going very well for some insect groups in the agricultural and urban area — but fortunately in many places, many insect species are doing well. The drama is possibly a bit smaller than what the media reports suggest."
As far as scientific data go, it's indeed hard to pin down.
Actual long-term scientific data on the abundance of insects are scarce – simply because no one was interested in this question decades ago.
Luckily, there are exceptions.
Insect biomass more than halved
Some troubling long-term studies in industrialized countries hint that an environmental disaster could be looming.
One study from the Krefeld Entomological Society in northwest Germany has become particularly well-known: a dedicated group of mostly amateur entomologists tracked insect abundance in a nature reserve near Krefeld since the 1980s by continuously trapping flying insects and weighing their catch.
Over 24 years, between 1989 and 2013, the trapped insect biomass had plummeted by 78 percent. This could mean two things: either larger insects are becoming less frequent — or there is a decrease in insects in general.
Researchers in the Netherlands had conducted a similar experiment, and came up with nearly the same result.
They caught ladybugs, ground beetles, mayflies, moths and others in two nature reserves in the Netherlands, and found an average population decline of 3 to 13 percent each year depending on the species. Only the number of true bugs hadn't dropped.
Researchers like Booij criticize that the studies in Germany and the Netherlands are "less robust than it is said," meaning he believes that the data are not precise and trustworthy enough.
Yet Josef Settele, an insect conservation and evolutionary biologist at Helmholtz Centre for Environmental Research in Halle, Germany, says that "it doesn't matter if the real decline is 80 or 60 percent — even 40 percent is simply too much."
Knowledge gap
While long-term studies on the overall number of insects in industrialized nations are already hard to find, they are almost nonexistent in developing countries in South America, Africa and Asia.
"Insect monitoring in those regions is still in their infancy," Josef Settele says. "Researchers over there have just begun to collect data."
Even the Food and Agriculture Organization of the United Nations doesn't have any global data on overall insect abundance.
What researchers have done in many countries across the world, however, is to monitor certain iconic or agriculturally important species.
And they have found that ever more insect species are declining, or even facing extinction.
This phenomenon can be observed across the globe, Josef Settele says.
"In tropical regions it's even more prevalent than in developed countries, due to deforestation and habitat loss."
Insect species on the brink of extinction
According to the International Union for Conservation of Nature (IUCN), populations for one-third of all insect species are declining.
IUCN even lists 273 insect species as "critically endangered."
The list of studies showing that insects are in danger is long. And it's not confined to Europe and North America.
Environmental researchers looked at butterfly fauna in a hill site in South Korea and found that the number of butterfly species had dropped 13 percent between 1999 and 2015, while the number of individuals across all species had plummeted by 70 percent.
"In addition to butterflies, large moths are also decreasing," lead author Sei Woong Choi tells DW. "I think this decease of fauna, known as defaunation, is now the common feature across the world."
Monarch butterflies losing ground
It's a wondrous spectacle: Each year countless monarch butterflies migrate thousands of miles south. The insect relies on its remarkable sense of direction — but numerous impacts are putting the insects off-track.
Image: picture-alliance/dpa/R. Loznak
One-of-a-kind
The monarch butterfly is a migrating marvel: It's the only insect that every year travels for two months and up to 5,000 kilometers (3,100 miles), from Canada and the United States to Mexico, where it spends the winter. There, the monarch butterfly roosts in the pine and fir forests in the Sierra Madre mountains west of Mexico City, which protect the insects, and help keep them from freezing.
Image: picture-alliance/dpa/R. Loznak
Mysterious insect
Not just the distance is amazing — also the butterflies' sense of direction fascinates scientists and experts. The monarch butterfly divides its migration over three generations, meaning no single butterfly lives long enough to make the roundtrip back to the US and Canada. And still, year in and year out, they seem to know exactly where they are heading.
Image: Reuters/C. Jasso
A perfect cycle
The butterfly synchronizes its lifecycle with milkweeds by laying its eggs on the plant in the US. In fall, when the milkweeds start to die, a young generation of monarch butterflies leave for Mexico. As soon as the first milkweeds appear in spring, the monarch butterfly returns to begin the cycle anew. There's evidence that they possess a genetically coded instinct for which direction to fly.
Image: imago/INSADCO
Agricultural pest
Milkweed is considered a pest in farming — industrial agricultural practices including monculture cropping and intensive pesticide use has decreased the plant that monarchs rely upon. It's one of the factors linked to monarch butterflies' decline.
Image: Reuters
Magnetic Compass
The baby butterflies that set off on the migration have never been to Mexico and therefore can't know the route. But still, the monarchs always find their way back to the Mexican reserve, where they wait out the winter. Studies in 2014 and 2016 suggest the sun offers orientation. In addition, the insects possess an inner magnetic compass corresponding to the Earth's magnetic field.
Image: picture-alliance/dpa/F. Poelking
Hard to count
Despite monarch butterflies being perfectly equipped to take on the vast distance each year, their numbers are decreasing nonetheless. It is hard to count individual butterflies, though, so experts came up with a specific method of assessing how many butterflies have migrated back to Mexico: They look at the area of forest the monarch butterfly covers.
Image: picture-alliance/dpa/F. Pölking
Declining numbers
And this area has declined dramatically. Since the winter of 1996-1997 it has shrunk, from about 44 acres (18 hectares) to 6 acres (2.5 hectares) in the winter of 2017. The reasons for this are diverse, among them more intense storms and busy hurricane seasons. Such extreme weather disturbs the insects' migration route and uproots trees, which the butterflies rely on in order to survive.
Image: picture-alliance/dpa/R. Blackwell
Competing with avocados
Other reasons for the butterflies' decline include illegal logging and land use changes. Monarch butterflies migrate to pine and fir forests that thrive at about the same altitude as prime avocado-growing land. In February 2018, Mexican police shut down an illegal avocado plantation that had been set up in the Monarch butterfly's overwintering grounds.
Image: Fotolia/fredredhat
No trees, no butterflies
On the positive side, Mexican officials claim to have nearly eliminated illegal logging in butterfly refuge zones. Fighting such deforestation is key, because the spectacular migration of thousands of Monarch butterflies can only continue if there are enough trees for the monarch butterfly to find shelter in.
His results are comparable to what researchers observed in the Central Valley of California during a 35-year survey showing that butterflies are declining on all study sites, both in species richness and in population.
This decline is even hitting insect species that are important food sources for humans.
In Benin, Africa, the International Institute for Tropical Agriculture has put together a red list of 34 endangered insect species. It includes the African Goliath beetle, an important protein source for people in central Africa.
Insects on the menu
The global food industry puts a major strain on the environment for many reasons and as the world population grows, the need for sustainable solutions in the area grows with it. Edible insects may have a role to play.
Image: Getty Images/S. Gallup
Locust lunch
With the global population increasing and the supply of agricultural land under threat — around a third of the world's arable land has been lost in the last 40 years — pressure is being put on the world's food supply. Then there is the strain meat production places on the environment. Many believe insects — such as the locust eaten here with an egg by a man in Tokyo — are a credible alternative.
Image: Getty Images/AFP/T. Yamanaka
Caterpillars in the Congo
Entomophagy is the name for the human use of insects as food. Humans have been eating insects since prehistoric times and today, most of the world's culinary cultures encorporate the eating of insects in some way. In the restaurant pictured here in the city of Kinshasa, DR Congo, a person is eating grilled caterpillars with olive oil. The food is cheap but provides a rich source of protein.
Image: Getty Images/AFP/J.D. Kannah
Making a meal of it
Despite its global ubiquity, there are many places, particularly in Europe and North America, where insect-eating is rare and treated with a certain reserve. However, there are signs that, prompted by the increasing promotion by environmentalists of insects as a sustainable food source, it is growing in popularity. In this image, Sydney chef Nowshad Alam Rasel displays a signature cricket dish.
Image: Getty Images/AFP/S. Khan
Crawlies creeping on to menus
But what's so sustainable about farming bugs? Compared with livestock farming, insect farming requires much less land and water and its greenhouse gas emissions are much lower. Insects need very little feed, and can themselves be used as sustainable feed for animals and fish. Increasingly, they are being used in high-end cuisine — in this Bangkok restaurant, winged ants are eaten with fish.
Image: Getty Images/AFP/L. Suwanrumpha
An alternative to palm oil?
Biteback, an Indonesian start-up, has been promoting insects as a nutrient-rich, sustainable alternative to palm oil, the cultivation of which is criticized for its environmental impacts, particularly in Indonesia and other Southeast Asian countries. The founders, pictured here making insect ramen, emphasize that insects are nutritious and have high fatty acids, protein and mineral content.
Image: Founders Valley/Biteback Indonesia
Worm lollipop
Global demand for meat is expected to increase by more than 75 percent by 2050. The amount of agricultural land and animal feed required for such production means the need for credible protein alternatives will intensify in the years ahead. Entomophagy enthusiasts point to insects' culinary flexibility — exemplifed in products such as the worm and cricket lollipops pictured here.
Image: Getty Images/AFP/K. Bleier
To eat bee, or not to eat bee
While insect-eating may well be a big part of the future of food, much development is needed in the sector. In trying to tantalize palates, unusual meals — such as this cake of roasted bees being eaten at a Berlin environmental fair — are being tried out. But given the pressure bee populations themselves are under worldwide, more practical insect-based meals may need to be dreamed up.
On the other hand, however, mosquitoes transmit malaria and other deadly diseases. Other insects such as locusts are agricultural pests that can even cause famines.
Especially in Africa, many insects are still seen as a danger for mankind, Michael Lattorff of the International Centre of Insect Physiology and Ecology (Icipe) in Kenya tells DW.
"Many small farmers simply don't know that some insects such as bees are useful."
Yet researchers haven't seen any decline in honeybee populations in African countries so far, Lattorff adds.
While honeybee colonies in Europe and North America are collapsing — due among other things to insecticides like neonicotinoids and parasitic Varroa mites harming the bees — honeybees in Africa are just fine.
Modern industrial agriculture provides only wastelands for insectsImage: picture-alliance/dpa/P. Pleul
Researchers found in 2014 that bees in Kenya stay healthy even though Varroa mites were present throughout the country, suggesting that the bees are more resistant.
But Lattorff cautions that insecticides are being used widely in African countries nowadays, and that often no regulations on pesticide use exist.
A survey back in 2013 showed that farmers in various parts Kenya do not follow pesticide usage advice — like avoiding application in the morning, when pollinators are active.
"We know very well which factors are impacting bees in developed countries," Lattorff says. And we might cautiously predict that bees — and maybe insects in general — will suffer the same fate over here if nothing is done to prevent it."
Dave Goulson, professor of biology at the University of Sussex in the UK, points out that other parts of the world are already starting to see the impacts of the loss of pollinators.
"Probably the best known example is in China where in parts of China they now hand-pollinate their apple and pear trees because they don't have enough bees left to do it."
The African honeybee is still doing fineImage: picture-alliance/Wildlife/M. Harvey
Not too late to act
Pesticides, monoculture, habitat loss and climate change are possible threats for insects, in industrialized as well as developing regions.
Not all insect species are declining, though — just as Booij pointed out.
Butterfly monitoring in Germany conducted by the Helmholtz Centre for Environmental Research in Leipzig found that the peacock butterfly is doing quite well, despite intensive agriculture.
These animals lay their eggs on the undersides of leaves of the stinging nettle — a plant that grows very well in nitrogen-rich, over-fertilized areas.
To conserve the richness in insect biodiversity, though, conservationists and researchers agree that it is time for a global change in agricultural practices, which would include using insecticides only in emergencies — such as to prevent a famine.
And you don't need to be a farmer to help the creepy crawlies survive.
"The neat thing about insects — unlike wolves, or polar bears, or Bengal tigers — is that insects are all around us. What we do in our everyday lives can really make a difference," Scott Black says.
Planting flowers in your garden and on your balcony will give those animals habitat — and the possibility to thrive.
"I believe there is still time to do something — if we take action now."
The wondrous world of African bugs
Though usually small, insects play an oversized role in Africa's huge and complex ecosystem. Some are helpful, some are dangerous. Some are simply dazzling. But together they are all an integral part of life in Africa.
Image: "Warren.K.Dick Photography"
The amazing Picasso bug
African art had a powerful influence on Picasso, did Picasso influence African insects? Otherwise known as the Zulu Hud Bug, this colorful shield-backed creature is often mistaken for a beetle. Its geometric design helps it blend into its surrounding and is meant to warn off predators. Full grown Picassos are only around 8 millimeters long and live in tropical Africa from Ivory Coast to Ethiopia.
Image: "Warren.K.Dick Photography"
Termite construction workers
Not many insects are known for their creative architectural abilities, but here termites in Namibia's central Otjozondjupa region have built amazingly tall structures in the savannah. Such mound-builders live throughout Africa, Australia and South America. Their complex structures full of tunnels cover a subterranean nest and are so well built they often outlive their termite builders.
Image: picture-alliance/ZB/M. Tödt
Giant devil's flower mantis
Looking like part of a fashion school project, the Idolomantis diabolica, more commonly known as the devil's flower mantis, is a jumble of shapes and colors. One of the largest praying mantis species, they are native to many East African nations like Tanzania. Mimicking leaves or a flower, these carnivore killers remain still until their favorite meal — airborne insects — flies by.
Image: Imago/Blickwinkel
The giant African fruit beetle
Another creepy crawly that tries to blend into its tropical African forest home is the giant African fruit beetle. The female is a bit smaller than the male which can grow to around 5 centimeters (2 inches) and has menacing looking horns. These beetles live off of fruits and sap flows from tree wounds. Also called the magnificent flower beetle, these mighty beasts can live up to five months.
Image: Imago/Blickwinkel
Butterflies and moths galore
One of the world's greatest experts on butterflies and moths was German entomologist Adalbert Seitz. Born in 1860, he edited the monumental 16-volume Macrolepidoptera of the World. Elaborately illustrated with over 200 color plates, four of its volumes were dedicated to the moths and butterflies of Africa. Started in 1907, the unfinished project was only stopped after Seitz's death.
Image: Colourbox
The killer mosquito
Not all insects are helpful and some are even downright dangerous. The tiny mosquito is at home on every continent except the Antarctic, but is especially bad for Africa. It only takes one bite from certain species of the Anopheles mosquito genus to transmit malaria and last year over 200 million people became ill with the disease. In Africa, a child dies of malaria every two minutes.
Image: picture-alliance/dpa/P. Pleul
A rainbow milkweed locust
One African insect that is not trying to blend in is Madagascar's vibrantly technicolored rainbow milkweed locust. As the name suggests, besides being colorful, this grasshoppers' diet consists primarily of milkweed, which makes it a highly toxic dinner for predators. Officially named Phymateus saxosus, these locusts can grow to about 10 centimeters (4 inches).
Image: picture-alliance/Wildlife/F. Teigler
The African honeybee
A subspecies of the Western honeybee, these social insects live in central and southern Africa. Slightly smaller than their European cousin they also produce less honey. But don't let their fuzzy upper body fool you — their sting is more potent than the Western honeybee. Yet despite their link to the "killer bees" spreading around the world these hard workers still have an important job to do.
