Bugs – many of us dislike them, some of us feel compelled to squish them; but what exactly is a bug, and why do they need our help? This article provides an introduction to the different types of “bugs”, their importance in the ecosystem and to humans, and some steps you could take to help protect them.
We often call any small thing with too many legs a bug, but these small critters can be very diverse, belonging to different taxonomic groups (groups of species based on relatedness). True bugs, which are insects, belong to the order called Hemiptera, while other “bugs” like spiders and millipedes are not insects at all, but they all belong to the arthropod group.
Abundance and diversity
Globally, arthropods make up 42% of animal biomass, compared to 2.5% made up by humans. As an example of how numerous they can be, there are an estimated 1.4 billion insects for every human on earth.
In terms of diversity, there are an estimated 1.2 – 2 million species on earth. Among these, up to 1.05 million are insects, making them the most species-rich group, outnumbering mammal species by nearly 160 to 1.
Despite the vast variety of insect species on earth, they remain under-represented in occurrence databases and published research. This poses a challenge to understanding global biodiversity and raises concerns about how well the scientific literature is representing the diversity of life on earth.
The number of insect species in Malaysia is not known, but new species are still being described every year. Insects are characterised by their six jointed legs, segmented bodies with three main parts, and an exoskeleton.
The largest group within insects, there are up to 400,000 species globally. Beetles can be identified by their hardened wing cases, which can be found in a remarkable variety of colours and textures. For example, the metallic green of tiger beetles, or the bright yellow scales of gold dust weevils, which give them an almost fuzzy appearance. Some beetles from the scarab family have been found to detect circularly polarised light, which is reflected by their iridescent bodies. This form of signalling is extremely rare in nature, and researchers speculate that it might help them communicate with each other while remaining cryptic from their predators. Beetles from the weevil family can be very round with long snouts, and are often considered cute.
Lepidopterans (butterflies and moths)
Another group with characteristic wings are the butterflies and moths, whose flattened wing scales often look like sequined fabric under a microscope. While butterflies receive more attention for their vibrant colours, moths make up a larger part of this group (18,000 species out of 160,000 Lepidoptera species globally). There are over 1,000 species of butterflies in Malaysia. Butterfly and moth larvae are some of the most important herbivores, driving the evolution of defensive mechanisms in plants. Some moths, like the clearwing Pyrophleps ellawi recently described from Peninsular Malaysia, mimic the appearance of other insects like wasps to avoid predation.
Flies can be recognised by their hindwings, which are modified into balancing organs called halteres, but many species are difficult to identify even for experienced entomologists. This group also includes mosquitos, midges, and crane flies. Some families of flies, like blowflies and flesh flies, are important in forensic entomology, where they are used to estimate the time of death when they are found in carcasses. They have been featured in many forensic entomology studies in Malaysia.
Hymenopterans (ants, bees, wasps)
Ants, bees, and wasps belong to the same order, usually identified by a narrow ‘waist’ and ovipositors (egg-laying organs) modified into stingers. This group contains many eusocial species, where individuals live in highly organised social groups. There are also many species of parasitoid wasps, which lay their eggs in other insect hosts. For example, the bright green Podagrion wasps found in Malaysia have thick hind legs which allow them to grasp onto female mantises until they lay eggs. The wasp lays its own eggs in the mantis eggs, then the wasp larvae emerge and eat the mantis eggs.
Hemipterans (true bugs)
True bugs have mouthparts adapted to sucking fluids out of plants, making many of them crop pests. Among these, the success of aphids may be partly explained by their rapid reproduction – females can give birth to live clones of themselves, which can already contain their own clones at birth. Another well-known group of true bugs are the cicadas, which can vibrate specialised membranes to produce the distinct sounds of tropical rainforests. Malaysia is home to the world’s largest cicada, the empress cicada.
What do bugs do?
Although some insects can cause damage in households and agricultural landscapes, the vast majority go about their lives unnoticed, conscientiously maintaining functioning ecosystems.
- Many insects are pollinators, transferring pollen between flowers to help plants bear fruit and set seeds. This is an essential service to the majority of plants and the wildlife relying on them, but also to humans as insect pollination underpins many important crops.
- Insects are vital food sources for wildlife populations at higher levels of the food web, with many species being reliant on insects alone. Similarly, insects regulate populations of other species, acting as pest control in some contexts. They have diverse roles as predators, herbivores, and as parasites of other animals. They are also decomposers, returning the nutrients from dead plants and animals back into the ecosystem.
Insects that are considered pests have their own roles in the ecosystem, and their status as pests sometimes reflects the consequences of human practices. For example, the proliferation of crop pests is promoted by cultivating large areas with a single crop. The cockroaches normally found in our homes are more likely to be species which were introduced to Malaysia through international trade.
How are bugs doing?
Globally, there is overwhelming evidence that insects are in decline, with reductions in the number of species, abundance, and biomass. There are many interrelated reasons for this, including land use change, climate change, habitat degradation, pollution, and invasive species.
In Malaysia, habitat loss is a major driver of insect declines. For example, the conversion of mangroves to plantations in Rembau have been linked to reductions in firefly populations.
How can we help?
As individuals, there are several ways we can protect insect diversity and help prevent further declines in their populations. First, to make habitats more bug-friendly, entomologists recommend these actions:
- Reducing the use of pesticides
While pesticides are sometimes needed, for example to control the spread of mosquito-borne diseases, extensive pesticide use can harm more than the target species, and may lead to pesticide resistance. Pesticides can remain effective in the environment for a long time, so they can travel far from the place of application, threatening arthropod populations in wide areas. Non-chemical interventions like window screens and removing potential pest breeding sites can be used instead.
- Preventing runoff containing household cleaning products
Household detergents like car wash soap can make their way into waterways, where they degrade and transform, producing compounds which can poison aquatic insects. Biodegradable detergents can be used as an alternative.
- Reducing outdoor lighting
As most nocturnal insects are attracted to light, light sources easily become death traps for nocturnal insects, which die from exhaustion or are eaten by predators while they swarm around lights. Light pollution can also disrupt insect behaviour and communication. Reducing or dimming outdoor lights is likely to help local nocturnal insect populations.
- Maintaining friendlier gardens
In grassy areas, leaving sections to grow undisturbed allows a more spatially diverse habitat to form, providing more space and resources for insects to use, while reducing the cost of maintaining manicured lawns. Growing native plant species can also benefit insects and the wider ecosystem.
Besides these, another important method to helping insect populations involves advocating for them:
- Negative perceptions of insects are still widespread, while recognition of the importance of insects may not be high. Talking to others about insects to foster an appreciation for them helps create interest in their protection.
- Sharing macro photos may also achieve this, as they illuminate the often striking visual details on insects.
- Participating in citizen science projects, such as the annual City Nature Challenge and uploading photo observations to iNaturalist can be an engaging way to learn more about insects while contributing to scientific efforts.
- Finally, reaching out to local councils and political leaders to advocate for insect-friendly practices and policies is another potential step to take.
Distribution of global biomass
Global biodiversity https://ourworldindata.org/biodiversity-and-wildlife#how-many-species-are-there
Beetles see circularly polarised light
Biodiversity research bias
1.4 billion insects for every human
Importance of insects
Wasp-mimicking clearwing moth
Flies in forensic entomology
Actions that individuals can take to save insects from declines https://www.pnas.org/doi/10.1073/pnas.2002547117
Insect classification – Royal Entomological Society
London natural history museum and ECOMY digitisation project for malaysian insects
Photos of Malaysian beetles (and other insects on the blog)
Checklist of Malaysian butterflies with photos – Nature Society Singapore
Places to find insect-related content on social media
Malaysian Nature Society Entomology Group
Video presentations on insects of Borneo by Malaysian entomologist Arthur Chung
Slow motion videos of insects in flight
Insect macro photography