Why Insects Matter

 

Insects are terrific pollinators!

As the growing human population transforms our planet, the global insect population is declining at an unprecedented rate of 2% a year. The world has lost 5% to 10% of all insect species just in the last 150 years, so in 40 more years we could lose one third of all insect species. In a study just published in the journal Science, a working group called the ‘Status of Butterflies in the U.S.’ found that the total abundance of butterflies in the U.S. declined by 22% from 2000 to 2020.  Said another way, one in five butterflies have vanished.

Many butterfly species, including the Monarch, are declining in abundance.

What is driving this precipitous drop in insect populations and why does it matter? Insect populations are struggling due to several factors, including deforestation/habitat loss (due to development), non-native invasive species, pesticide use, artificial light pollution, and climate change.  As a result, the populations of other animals, crops, and flowers that rely on insects to survive also struggle.

Non-native, invasive plants, like Ligustrum species, often overtake native habitats.

Scientists say that it is impossible to have an insect-free life on this planet. They perform many essential services that are vital for humans’ quality of life. Pollinators such as bees, butterflies, moths, and many other types of insects are necessary to produce diversity and abundance in our food supply, including crops such as coffee, chocolate, blueberries, apples, almonds, avocados, and pumpkins, just to name a few. In fact, pollinators help ensure that about 75% of the world’s flowering plants and 35% of the world’s food crops are produced.  Other scientists estimate that one out of every three bites of human food are directly related to the work of pollinators such as bees, butterflies, moths, beetles, and other insects.

Moths and beetles are pollinators, too!

Plant and animal waste would pile up if it weren’t for the services of dung beetles and other insect recyclers. Insects like dragonflies, ladybugs, green lacewings, ground beetles, and parasitic wasps keep what we call the ‘pest’ species at bay – the mosquitos, ticks, fleas, lice, and flies that can carry disease as well as crop pests such as armyworms, cutworms, and wireworms.  

Dung Beetles hard at work.

Roseate Skimmer dragonfly eating a mosquito.

Most humans like birds, but most are also unaware of the fact that 96% of birds would not be here without insects. It takes 6,000 to 9,000 caterpillars and other insects to feed a clutch of four to six Carolina Chickadee offspring. Multiply that by the fact that most all avian nestlings and fledglings eat some form of insects, and you very quickly realize how important they are to the food web. Insects are also the main food for all of the fish, so they are the glue that binds together every terrestrial and freshwater ecosystem on the planet.

Many bird species, like the endangered Golden-cheeked Warbler,
feed insects to their young.

What can be done to reduce this downward trend?  The good news is that the things we do in our own backyards can actually make a difference when it comes to insect conservation. First and foremost, reduce or (better yet) replace your non-native lawn with native plants.  Lawns make up about 50% of Austin’s green space, so turning them back into native plantings would provide significant benefit to insects. 

Replace your lawn with native plants -
extra bonus for providing water!

Eliminate all pesticide use, including mosquito spraying. The spray contains pyrethroids which are advertised as “safe as chrysanthemum flowers”, but they are a much stronger synthetic version that is chemically designed to be more toxic with longer breakdown times.  This increased potency compromises the human body’s ability to detoxify the pesticide in addition to killing all insects, not just mosquitos.

Mosquito spraying kills all insects,
not just mosquitos.

Light pollution contributes to insect decline.

And last, but not least, turn your exterior lights off at night so as not to affect the behavior of night-flying insects (this also benefits birds during spring and fall migration). Artificial lighting can disorient moths and confuse their sense of direction, causing one third of those that swirl around a light at night to die from exhaustion or predation. Excess light also disrupts the mating flashes of fireflies and confuses insects like mayflies by bouncing light off of asphalt and causing them to lay their eggs in the street instead of in a lake or stream.

Requisite Night

 

Light pollution is nearly non-existent in Big Bend,
allowing for spectacular star-filled night skies.

Most environmentally-minded individuals recognize the more talked about threats to our native wildlife, such as habitat fragmentation/loss, invasive species, and climate change, but not as many are aware of the dangers posed by light pollution. Up until the mid-1800s, humans and animals lived under night skies solely lit by the moon. Electric outdoor lighting became common in the early 20th century, but its use spread quickly, and the global extent of modern light pollution became clear.  

By 2016, it was possible to measure nocturnal artificial light with the advent of a comprehensive global satellite measurement system. Researchers found that more than 80% of the world’s population lived under light-polluted night skies, or skies where the glow of artificial light is significant enough that the stars disappear from view.  In the US and Europe, it was found that 99% of residents live under light-polluted skies.

Light pollution exposes animals to many dangers, including predators, starvation, exhaustion, and disorientation. Artificial light, like roads and fences, can create barriers that fragment habitat.  Slow-flying bats avoid feeding in or passing through illuminated areas for fear of predators such as owls and other birds of prey. Artificial light near their roosts can also delay their emergence at dusk when their insect prey is most abundant.  If they never leave their roost since it always appears to be light, they can even starve to death.  

Artificial nocturnal light can also lure animals in and lead to their destruction.  Many species of migratory songbirds are attracted to brightly lit structures at night, circling them, sometimes colliding into them, or becoming disoriented enough to lead to a depletion their energy stores which ends in exhaustion and the inability to complete their journey.  In some bird species, artificial light at night interferes with their ability to use natural polarized light from the sky to calibrate their internal compass.

Artificial light at night attracts insects, like this Luna Moth, 
and can disrupt normal behavior patterns.

Light pollution is also one of the many factors contributing to the rapid decline of insect populations.  Moths and other nocturnal insects orient themselves by moonlight, and this instinctual tendency is interrupted by artificial night light, luring them in to fly incessantly around a bright light, causing exhaustion, exposure to predators, and the potential to miss courtship cues from mates.  This is especially true for fireflies, as artificial night light can cause them to alter or cease their mating flashes.  Studies have also shown that light pollution can harm diurnal insects like monarchs, who flit and flutter all night when exposed to excessive light when they should be resting, and causing them to be disoriented from their migration route.

Light pollution facts and some easy solutions.

Unlike other environmental threats to wildlife, simple solutions to artificial nocturnal light exist.  The best solution is to have no nocturnal lighting other than natural conditions. If a light at night is truly needed, the amount that spills into wildlife habitat can be reduced through dimming, downward shielding, or switching to motion-activated lights. Studies are also showing that lights in the warmer color tones are less disruptive than bright white lights.

Travis Audubon promotes the Lights Out Initiative for Austin.

Austin is one of several cities across the US that participates in the migratory bird friendly Lights Out Initiative, which asks residents to turn out all non-essential lights from 11pm to 6am every night during spring migration (March 1 – June 15) and fall migration (August 15 – November 30).  This is one of many ways we can prevent light pollution from overpowering our native wildlife. Turn out your lights when they are not needed, and welcome the requisite night!