There is an old entomological axiom—all (true) bugs are insects but not all insects are bugs. Bugs are insects that belong to the order Hemiptera, but the generic name has been hijacked to address any creature that crawls, bites or stings. Thus, earthworms, leeches, millipedes, spiders, cockroaches, snails and crickets are all bugs! Hemipterans have every reason to feel bugged. Entomologists, therefore, refer to this group of insects as “true bugs”. This is like how dipterans are called true flies to differentiate them from the innumerable insects whose names end with “fly”, such as butterfly, dragonfly and eyefly.
So who are bugs? In Lucy Clausen’s words, they are “insect hypodermics”, or insects with specialised piercing and sucking mouthparts. If only plants could talk, they would vividly describe the injuries these insects inflict on them. Despite many creatures such as the aphids, hoppers and bedbugs that wreak havoc on other creatures and humans, there are a great many of them that lead a far more interesting life, helping humans and other creatures.
In describing true bugs as “agricultural pests”, we are actually doing them a disservice and completely forgetting the ecological services they provide. Their diversity, behaviour and ecology are complex. Bite they will, but from a human perspective, it can be said that the bites are not without benefits. The friendly bug’s bites keep plant pests in check.
Hemiptera literally means “half wing”. The top part of the forewing is thick, while the end is membranous, thus appearing as though half the wing is a different part of its body. This is the easiest feature to recognise those bugs that are otherwise mistaken for beetles. However, they are, like many in the insect world, quite diverse in their appearance.
It is the fifth largest group among insects. They are so different in form and habits despite the fundamental similarity of wing style that entomologists have divided this order into four subgroups, namely, Sternorrhyncha, Auchenorrhyncha, Coleorrhyncha and Heteroptera.
A motley group such as this is not seen in any other insect order. Their sheer diversity—of habit, tenacity to survive, ability to occupy nooks and corners of not just non-living but living things—fascinates entomologists. As they love to chew the very food that humans grow, these are job providers for agricultural scientists. Several are predators, too, hunting and destroying their brethren who harm crops. Too diverse to be described in a few words, I have chosen to share details of those bugs that have fascinated me or have had a long cultural association with humanity in general.
The singing bug: cicada
The insect community’s most loud and vocal representative is the cicada. Their calls are strikingly different: from sounds like a chainsaw in a logging depot, a welding machine, anklet bells, an idling car, a moving train and an aeroplane taking off to disconnected notes that may sound like a series of aahs and ohhhs, their responses to sounds are as varied as their calls.
To the Greeks their calls herald good times.
Don’t trust the frog or the swallow.
If the cicada doesn’t chirrup, it’s not summer.
This epigram is part of the harvest song from Greece that spans centuries, sung from 1860 until now. For tourists visiting Provence, a beautiful Mediterranean region in south-eastern France bordering Italy and a favourite destination in summer, the cicada’s sound is a sleep-depriving cacophony. When a complaint went to the local Mayor for silencing them permanently, the Provencals flatly refused and treated the demand with disdain. For Provencals, the cicada was a symbol of peace and its call at 7 a.m. a musical alarm. For entomologists, its calls are a way to differentiate one species from the other.
The Greeks and the Chinese have perhaps the longest-lasting association with this insect, older than the Egyptian’s reverence for the scarab beetle. The cicada was a symbol of rebirth and immortality. What led to such a belief? The cicada’s eggs hatch beneath the soil, where the young take anywhere from months to several years to become an adult. They emerge from the ground in a freshly moulted state.
Although Aristotle described these events in his book Historia animalium (History of Animals) in the fourth century B.C., this emergence from the ground (seen as coming from the womb of the earth) was the basis of the symbolism. An early reference to the cicada’s songs can be found in Homer’s Illiad , where he compares the “shrill” voices of elderly men in heated conversation to that of the cicada’s calls.
The cicada was a symbol of transformation and resurrection in ancient China and was part of funeral proceedings. During the Han period, jade amulets in the shape of cicadas were placed in the mouth of the deceased under the tongue. This was part of the ritual to plug the nine orifices of the body with jade amulets in order to prevent decay. The tongue amulet was the most important as it represented the everlastingness of the soul to escape decay and attain immortality. So strong and widespread was this belief that when a king or an emperor died, princes from other provinces sent cicada-shaped tongue amulets to be placed in the mouth as a mark of respect.
The cicada’s way of life attracted the attention of not only ancient cultures but modern ones too. Chremistica ribhoi is a cicada that is found in the Ri-Boi district of Meghalaya. Its range is restricted to two small villages. It is known locally as Niangtasar and more famously as the football cicada. This cicada has a four-year cycle of growth. The adult’s emergence once every four years coincides with the football World Cup. The cicada moults soon after emergence. The villagers collect the imago (before moulting) and use it both as food and fish bait.
Cicadas are also used in medicine by the Chinese. The moulted skin of the cicada, called Chantui, is collected for several medicinal preparations. A medical text, “Mingyi Bielu”, published in 500 A.D. by the renowned physician Tao Hongjing contains this quote: “Cicada relieves itching by eliminating wind, and is indicated for urticaria and pruritis. Moreover it relieves optic nebulae and congestion of the eyes.”
But it is the call that is the cicada’s signature. How does the cicada produce such a loud sound? It does so with the help of a specialised structure called tymbal, which varies from species to species depending on surface geometry, curvature and the number and shape of the thickenings called ribs. There is one tymbal on either side of the abdomen, attached to muscles. When the muscles tug them, their shape changes, thereby producing the sound. But there are some cicadas, especially the females of some species, that produce a clicking sound by flicking their wings. Wing clicks are predominant in Australian and New Zealand species. A few species of cicadas produce sound by stridulation, in which the wings are rubbed against the roughened edges of the skin. One family of cicada produces sound by vibrating the substrate such as the soil or plants on which they stand. The sounds are produced for a variety of reasons: establishing territory, announcing their presence, for courtship, to raise an alarm or indicating distress.
The aquatic bugs
Sreemoyee Basu and K.A. Subramaniam of the Zoological Survey of India report that there are 325 species of aquatic bugs from 18 families living in freshwater habitats in India.
Water striders belong to the family Gerridae. You cannot miss their strides in water. They dart about on the surface of water, skating rather than striding. Hence, they are also called pond skaters. They are among the few creatures that live in a specialised habitat; their lives are spent on that thin layer of the water surface where air meets water. At this air-water interface, water molecules behave slightly differently. The molecules’ attraction for one another is so strong that they form something like a continuous film, a thin membrane on the surface, and in the process cause what is known as surface tension.
The thin membranous water surface is the habitat of the skater. On this thin surface, they not only walk but run hither and thither, even on a rainy day. How do they manage this? The secret lies in their thin long bodies and the three pairs of long legs, of which the middle one is especially adapted to take advantage of the surface tension.
The insect uses its middle pair of legs as paddles to “row”. When we row a boat, the oars create swirling vortices in water that help the boat to move forward. When this insect “rows”, swirling vortices are created by microscopic hairs found on its legs. These hairs have a waxy covering that keeps the water out and thin grooves that trap air to keep the insect buoyant. So with two more pairs of legs to move, the insect merrily goes about its life frolicking on water.
The front pair of legs is shorter and helps it capture prey on water, generally mosquito larvae. If there is a shortage of food, it turns cannibalistic and does not hesitate to eat its own. But not all scientists agree on this. Some have suggested that it may be a fluid feeder. So the last word has not yet been heard about its feeding preferences.
The last pair of legs also helps in locomotion. They are the longest and help in steering and braking. Watch a skater dash about in water! It can generate a speed of hundred body lengths per second. But there is more to these legs. There is research under way to discover the chemistry of the waxy legs to create new waterproof materials.
The males are a dominant lot and will resort to blackmailing the females into mating with them. In the water, the skater’s predators are another group of insects called backswimmers and fish, which attack them from below the water. During mating, a male mounts the female, and if she refuses to mate with him, then he drums on the water to attract predators. The female, which is just above the water surface, is in danger of being attacked and eaten, whereas the males can simply get off and run away. While some females give in, others use the spines on their body to try and toss away the male. Expecting such an action, in some species of skaters, the males pin down the females using the spines on their front legs.
These insects may be short-winged, long-winged or wingless, depending on the environmental conditions they experience. Non-winged individuals find it easy to stay on water without drowning. But when their habitat gets overcrowded or dries up, then a winged form can migrate to a new waterbody. The ability to produce a generation of winged or non-winged young ones is another adaptation for survival in these insects.
It is the ability to adapt in such sophisticated ways that makes insects the most successful creatures of this planet. The next time you visit a waterbody, look out for these insects. A word of caution, though.
There is also another kind of insect inhabiting such waters. They are the water measurers. They are longer and thinner than the water skaters and possess long antennae. Their long body resembles a yardstick, hence the name. They are more common in marshes and stagnant water. But the water striders are seen in a variety of habitats, including the oceans. They are among the very few ones that live in marine waters.
Giant water bug
The bugs belonging to the family Belostomatidae have become model organisms for researchers. Among the largest insects is the giant water bug Lethocerus indicus . This is a sought-after bug by academics, and they are considered a tasty snack in South-East Asia. The scientific world seeks it to get a better understanding of the human heart muscles.
The rhythmic contraction of the human heart muscle is similar to the contraction of the muscles insects use to fly. The way the working of the muscles is controlled and coordinated is different in insects and is of interest to researchers. A better understanding of the working of the flight muscles will help scientists understand and address problems relating to cardiomyopathy, or failure of the heart muscle. Lethocerus is a big insect, so it is easy to dissect and remove the flight muscles. Moreover, the highly ordered structure of the insect’s muscle fibres produces X-ray diffraction images rich in detail, better than what vertebrate muscle fibres can give.
This insect is found in freshwater ponds, marshes and streams and is a fierce predator. Fish, amphibians, crustaceans, snails and aquatic invertebrates are its common food sources. The front pair of legs is its weapon, modified to capture these animals, some of them quite large. There have been instances of this insect preying on water snakes and baby turtles. It can give you a nasty nip if you try to pick it up. On a night wet with dew or a drizzle, you will find it attracted to light to feed on even terrestrial insects. It injects a fluid through its bite to poison its prey, but it is not venomous to humans. The males of the species are excellent parents and spend a considerable amount of time guarding the eggs that are laid on vegetation. In some species, the eggs are laid on the wings of the male, which then carries them around until the young hatch.
In South-East Asia the bug is relished as a snack. Roasted, it makes for a crunchy delight; cooked with chillies, it is a tasty side dish. An assortment of true bugs are part of the food consumed by Asians and other indigenous communities across the world.
From the records available, communities that consume hemipterans are found mostly in the north-eastern region in India. Arunachal Pradesh leads, with its people feasting on 102 types of insects. The Nyishi of East Kameng and the Galo of West Siang in the State consume 16 different species of hemipteran bugs.
Known variously as tari, paahu or gandhi puk, species of the stink bug Coridius are consumed, mainly during winter, by communities such as Adi, Apatani, Nocte, Mishmi and Wangchoo of Arunachal Pradesh. However, this bug can produce hallucinations and an intoxicated state when it is consumed without removing parts of its abdomen that produce chemicals meant to protect it from predators. How should a bug or any edible insect be treated to make it fit for consumption? This knowledge rests with indigenous communities and is yet to be documented adequately in our country.
Bugs of the hemipteran order come in all shapes and sizes. Stink bugs, assassins, cotton stainers, seed bugs, water scorpions, backswimmers, brilliantly coloured planthoppers and their close cousins leafhoppers, froghoppers, treehoppers, the infamous aphids, scales, mealy bugs and bedbugs are some among the many colourful characters that share the planet with us. I have not even skimmed the surface enough. Scientists across the globe fear that insect diversity is on a decline. Will insects disappear so fast? That is a story for another day.
Insect Fact and Folklore by Lucy Clausen.
Heat and Lust: Hesiod's Midsummer Festival Scene Revisited by John Petropoulos
https://www.insects.orkin.com/ced/issue-3/cicadas-in-ancient-greece/ Cicada in culture
Chakravorty et al. Journal of Ethnobiology and Ethnomedicine 2011, 7:5