Why should I want bugs, insects, and creepy crawlies in my yard or garden?
Insects are an incredibly diverse group of organisms, with 91,000 described species in the United States and likely an equal number yet to be described by scientists. Only an exceedingly small fraction of these species ever have negative impacts on humans as “pests” (<1% of species). Often the overabundance of pest species is due to human agricultural and landscape practice choices. The vast majority of insects in shared spaces with humans like yards and parks are going about their own lives. In addition to being fascinating creatures deserving of habitat in their own right, they also often contribute to unnoticed but very important tasks that help humans, termed “ecosystem services.” The next time you see one of these critters in your yard, consider thanking them rather than smashing them.
What are ecosystem services?
Ecosystem services are benefits that humans gain from the environment. Examples of ecosystem services include water filtration, raw material production, erosion control, and pollination. Some ecosystem services, like the maintenance of atmospheric gasses (e.g. plants remove carbon dioxide and produce oxygen that humans breathe), are noticeable and directly impact our everyday lives. On the other hand, services like decomposition may go unnoticed because they indirectly affect us.
Insects (and their arthropod relatives like spiders and earthworms) play vital roles in many ecosystem services. This is often due to insects interacting with plants in some way, though insects also provide food for many other animals. Below are some examples of the ecosystem services that insects contribute to.
Water filtration
Filter-feeding insects positively affect water quality because they remove particles of dead organic material. Insects retain many of the nutrients they filter out of the water, thus reducing the likelihood of algal blooms, their associated toxins, and dissolved oxygen “dead zones.” This is crucial because clean water provides habitat for other plants and animals like fish and amphibians. It also means less effort is required to purify water for human use.
Types of insects that improve water quality:
Blackflies, mayflies, stoneflies, and caddisflies (Note: the underlined insect groups are not “true” flies in the taxonomic Order Diptera; they are part of other orders.)
Other types of organisms that improve water quality:
Mussels, crayfish, snails
More information:
[Click to view full video on Flickr] A blackfly larva attached to the side of a tank and filter feeding on particles that float by in the water. Credit: Donald Hines, CC BY 2.0 DEED
Biocontrol
Biocontrol is when natural enemies are used to suppress pests and reduce the amount of damage they cause. Natural enemies are insects that are antagonistic to pest insects. There are three types of natural enemies: predators, parasitoids, and pathogens. Preserving natural enemy populations is crucial to reducing our reliance on pesticides because when natural enemies are active, pest outbreaks are less likely to occur in the first place. Predators need food all year, so they also need alternate prey available in order to prevent pest outbreaks. Pesticides eliminate beneficial insects in addition to pests, so they should be used only as a last resort.
Fun fact: Fireflies spend much of the year as larval predators belowground, feeding on pests like grubs in turfgrass yards. If no prey is available in yards, then there will be no display of adult fireflies in the summer.
Types of insects used for biocontrol:
Beetles, lacewings, wasps, and dragonflies
Other types of organisms used for biocontrol:
Fungi, birds, amphibians, reptiles, and mammals
More information:
An adult samurai wasp lays eggs in a mass of brown marmorated stink bug eggs. Credit: Chris Hedstrom, CC BY-SA 2.0 DEED
Seed dispersal
Seed dispersal is when seeds are moved away from the parent plant. Seeds are moved when insects knock them off while feeding or when insects collect and then move seeds to a new location. Seed dispersal is important because it reduces resource competition between the parent plant and offspring plants. It also makes germination and seedling survival more likely, especially in arid climates.
Types of insect seed dispersers:
Ants (most effective), beetles, wasps, thrips, and some moths
Other types of seed dispersers:
Fruit-eating animals (frugivores), such as some monkeys, lizards, and bats
Unwitting animal dispersers of sticky seeds like this
More information:
Two ants carrying a plant seed. Credit: Mark Chinnick, CC BY-NC-ND 2.0 DEED
Decomposition/Nutrient Cycling
Nutrient cycling and decomposition are two important processes that rely on one another. Nutrient cycling is when soil nutrients are taken up by plants, insects eat plants, and then those nutrients are reintroduced into the soil when dead insects and droppings are broken back down into nutrients via decomposition. Decomposer insects help clear dead animals and plants off the ground which would otherwise accumulate everywhere. They also help create soil texture and circulate nutrients back into the soil, which plant populations and productivity depend on.
Types of insect decomposers:
Many beetles, springtails, termites, wood cockroaches, and some fly larvae (maggots)
Other types of decomposers:
Fungi, earthworms, pillbugs, and millipedes
More information:
An adult bess beetle crawls across a log. Bess beetles are important decomposers and return nutrients to the soil. Credit: Kelsey McGurrin, used with permission.
Supporting Food Webs
Insects are a main source of protein and nutrition for many animals (and even some plants). They play a crucial role in transferring energy from plants to larger animals that eat insects like spiders, birds, frogs, fish, bats, foxes, opossums, and bears. This wide food base that they provide allows for functioning, stable ecosystems that are resilient to disruptions.
Fun fact: By weight, there are roughly 300 times more insects than humans on Earth.
There are so many animals that eat insects, but here are just a few examples:
Terrestrial bird species, in particular, feed their babies almost exclusively with insects, and if there are fewer insects, baby birds are less successful at fledging from nests.
Popular fish like salmon, bass, and trout eat insects, especially when they’re young
Grizzly bears will eat tens of thousands of moths a day to prepare for hibernation
Northern Mockingbird adult feeding a praying mantis to a young bird. Credit: Becky Matsubara, CC BY 4.0 DEED
Pollination
Pollination is the transfer of pollen between flowers, resulting in flower fertilization and seed/fruit production. It is an unintentional consequence of pollinators going from flower to flower to feed themselves. Pollination is crucial for human survival, as 80% of plant-based foods and products rely on animal pollination. According to the USDA, pollinated crops are worth $18 billion in the US alone. Foods requiring pollination include apples, blueberries, chocolate, coffee, grapefruit, peaches, peppermint, sugarcane, tequila, and vanilla.
Fun fact: beetles were likely the first insect pollinators- starting 200 million years ago!
Types of insect pollinators:
Bees, wasps, beetles, flies, ants, butterflies, and moths
Other types of pollinators:
Birds and bats
More information:
Blueberry Digger Bee pollinating blueberry flowers. Credit: Judy Gallagher, CC BY 2.0 DEED