The Ground-Dwelling Songsters of the Insect World

ORTHOPTERA recorded around the world but many more are still waiting to be discovered and described. Grasshoppers belong to the suborder Caelifera, and are distinguished The Ground-dwelling Songsters from crickets and katydids (suborder Ensifera) by their shorter antennae. The antennae of a grasshopper generally of the Insect World consist of about 20 segments whereas those of crickets and katydids are much Three local entomologists have taken it upon themselves to study a difficult to longer. In agriculture, some grasshoppers – the locusts – are deemed as pests find and identify group of insects in Singapore, and here they share some of that destroy crops across their migratory their results with the rest of us. path and can cause millions of dol- lars worth of loss. However, only very Text by Tan Ming Kai, Robin Ngiam and Mirza Rifqi bin Ismail few species from the family Acrididae enter this swarming phase, and human s day turned into night, activities greatly contribute to these the cicada-dominated swarming incidents. Clearance and/or soundscape in our modifications of grasshopper habitats nature reserve was slowly result in the lack of food and space, replaced by a gentler forcing these locusts to form destructive chirping call. This sound, unlike that mobile swarms. In actual fact, grasshop- Aof the cicadas, was coming from the pers are not just a destructive force, ground. We rummaged through the for- they also provide services to us. For est and our curiosity eventually brought instance, grasshoppers are served as a us to the ground-dwelling songster. food in many countries, and they might There it was, this innocuous cricket, a constitute a more ecologically friendly member of the Gryllinae subfamily of food than, for example, poultry. This the Orthoptera, an insect order that is is because insects require less space and relatively little known. resources for breeding and yet they can provide us with necessary nutrients. It Grasshoppers, crickets and A common and typical looking grasshopper, here a pair of Xenocatantops humilis caught has even been postulated that insects as katydids. What are they? in a tender moment. Photo Tan Ming Kai food can be a healthy solution to the Orthoptera (meaning ‘regular wings’ in worldwide problem of hunger. And Latin) is an order that consists of the Although grasshoppers and crickets are commonly who says grasshoppers are just green insects commonly known as grasshop- A Gryllinae male calling out at the opening of the burrow to attract potential mates. The assumed to inhabit grasslands, orthopterans in general and brown? Contrary to popular belief, pers, crickets and katydids. They are calls can be deafening at close distance. Photo Robin Ngiam many grasshoppers, just as many other generally characterised by having their can be found in nearly every terrestrial ecosystem. orthopterans, are beautifully coloured hind legs modified for jumping, by their They inhabit forests, deserts, woodland and scrub. and they come in all shapes and sizes. ability to produce sounds, by having Species such as the blue monkey grass- ventrally facing mouthparts for chewing, hopper (Erucius species), leaf mimicking and by their leathery forewings for fly- grasshopper (Systella rafflesii) and spiky ing. Some orthopterans can be found in pygmy grasshopper add brilliance and parks and gardens, but many are found splendour to our natural landscape. in less manicured landscapes. Although Crickets are even more interest- grasshoppers and crickets are commonly ing than grasshoppers. Some imported assumed to inhabit grasslands, orthop- crickets are sold as food for pets in terans in general can be found in nearly aquarium and bird shops, but many every terrestrial ecosystem. They inhabit fascinating crickets that are native to forests, deserts, woodland and scrub. Singapore are unknown to most people Within these ecosystems, orthopterans here. For example, leaf-rolling crickets can be found in a variety of microhabi- exhibit an unusual behaviour by hid- tats, from beneath the leaf litter right ing in leaves rolled up and ‘stitched’ by up to the top of the canopy, on boul- silken threads. They are sometimes also ders in the middle of streams and even known as raspy crickets, as they exhibit on mudflats at low tide. So far, nearly A species of monkey grasshopper, Erucius sp, from Hose Mountain, Sarawak. defensive behaviour by producing rasp- 20,000 orthopteran species have been Photo Robin Ngiam A leaf mimicking grasshopper, Systella rafflesii. Photo Tan Ming Kai ing sounds. Another interesting behav- 8 Nature Watch Jan - Mar 2012 Jan - Mar 2012 Nature Watch 9 iour is shown by ant crickets. These and as pugilists for their relaxation and small crickets live in ant nests and these amusement. In China and associations are often species-specific. Perhaps the most discrete group Evolution has shaped the appearance of orthopterans is the katydids. While Japan, people of crickets and produced unique ana- there are six families each of grasshop- tomical features. For example, mole pers and crickets, all katydids belong used to keep crickets have modified forelegs adapted to the same family, Tettigoniidae. for digging burrows, while scaly crickets The word ‘katydid’ is derived from crickets as music- have tiny scales on their body to help the sound produced by the males of a them escape when seized by predators. subfamily of katydids, known as leaf- making pets and Crickets are also an important part of mimicking katydids (Pseudophyllinae). culture in Asian countries; where they When disturbed, many species in this as pugilists for are highly regarded. For instance, in group will adopt a cryptic position by China and Japan, where people used expanding their forewings to blend into their relaxation to keep crickets as music-making pets the leaves they are sitting on. and amusement. Eat and be eaten The diet of Orthopterans varies from completely herbivorous to mixed to completely carnivorous. One common carnivorous orthopteran is Hexacentrus unicolor (family Tettigoniidae) which actively hunts for other insects, sometimes including prey larger than itself. Many orthopteran species are also A spiky pygmy grasshopper from Hose Mountain, Sarawak. opportunistic feeders, feeding on Photo Robin Ngiam whatever is available. For example, many cone-headed katydids (subfamily Conocephalinae) generally feed on grass- The nymph of a typical looking cricket, Cardiodactylus sp. es and seeds but may also feed on small Photo Robin Ngiam insects and insect eggs when available. Orthopterans themselves serve as food for many predators. These range from small invertebrates such as ants Left: A leaf mimicking katydid or true katydid, Chondroderella borneensis. Photo Mirza Rifiq bin Ismail The nymph of Hexacentrus unicolor prey- ing on another orthopteran originally of a larger size. Photo Robin Ngiam 10 Nature Watch Jan - Mar 2012 Jan - Mar 2012 Nature Watch 11 and spiders to larger vertebrates such as the male, the couple will begin their are eaten as a source of nutrition. Apart lizards, frogs and birds. Thus, orthopter- ‘foreplay’ which is then followed by from this and other basic knowledge, ans play an essential role in ecosystems, copulation. Sexual positions are varied we have yet to unravel the mystery of functioning both as predator and prey. in the orthopteran world and are best orthopteran life history. described via pictures and illustrations. Sex and reproduction Different orthopterans lay their eggs in Locomotion To attract a female, Orthopteran males different substrates. Grasshoppers usu- The modified hind legs of orthopter- will ‘sing’ their hearts out, despite ally lay their eggs in the ground; while ans allow for great jumping ability. exposing their location to potential katydids and crickets insert their eggs However, some orthopterans posses predators. Males of each species display into soil or the stems of plants and modified legs for other modes of move- a unique ‘song’ that only their female leaves. ment. For example, the common rice counterparts are attracted to. These calls grasshopper (Oxya japonica) has modi- are often inaudible to the human ear. Growing up fied hind tibiae that are expanded like The grasshopper males will rub their Orthopterans undergo an incomplete a leaf-blade, to allow it to wade over hind legs against their sternum to pro- metamorphosis in which the nymph of the surface of water in flooded rice Mating position of a pair of Atractomorpha Mating position of a pair of raspy crickets, A female cone-head katydid, Conocephalus duce stridulation, whereas cricket and each juvenile stage resembles the adult fields. In more extreme cases, some species, typical of most grasshoppers. The Larnaca sp. Photo Robin Ngiam melaenus, emerging from its exoskeleton male is generally smaller and holds on to during the final moult from the final instar katydid males will vibrate their forew- except for its size, wings and sexual pygmy grasshoppers (family Tetrigidae) the larger female at the bottom. Photo Tan of the nymph to the adult. Photo Robin ings to produce sound. The females characters. At each juvenile stage, the are known to dive and remain sub- Ming Kai Ngiam pick up the vibrations with their ‘ears’ nymph grows larger and moults, shed- merged in the water of small streams or tympana located near the base of the ding its exoskeleton. For crickets and for several minutes. Moreover, some Perhaps a dedicated area within a park forelegs. After the female approaches katydids, the exoskeletons once moulted species of the cone-headed katydid where grasses are allowed to grow wild (tribe Copiphorini) use their forelegs would encourage common orthopterans To attract a female, Orthopteran males will ‘sing’ to gracefully hold onto a seed as they to take up residence and enhance our chew it. Many orthopteran species urban biodiversity. A healthy orthop- their hearts out, despite exposing their location with fully developed wings are also teran population can also attract other capable of flight.

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