Insect Orders (3): Bugs (Hemiptera)
Above: Hemipterans have very diverse body forms and many can be easily mistaken for other insect groups by the layman, such as the two Ricaniid hoppers above, which are often misidentified as moths.
Introduction
True bugs, or Hemipterans, are common insects with a cosmopolitan distribution. Hemiptera means "half-wing", a trait notable in the larger true bugs like stink bugs and assassin bugs. The defining trait of Hemipterans is the sucking mouthparts that they possess, which is also known as a proboscis. This trait is not exclusive to the Hemipterans, however, as mosquitoes and Lepidopterans (butterflies and moths) possess sucking mouthparts too. This order of insects is extremely diverse, with much variation in body form, feeding habits and habitation. The more well-known members of Hemiptera include aphids, stink bugs, cicadas and water striders.
Above: A beautiful giant stinkbug (Tessaratomidae).
Life Cycle
Hemipterans are hemimetabolous, which means that they undergo incomplete metamorphosis. The juveniles look like miniature versions of the adults, but they lack wings. As they feed and grow, they will have to moult and eventually, after their final moult, they will develop wings. The adults of some true bugs are able to procreate via parthenogenesis, in which the females are able to produce young without the need for a male. Most particular are the female aphids being born with developing young already in their bodies, an adaptation that allows for quick population booms that frustrate farmers all over the world.
Above: Nymphs of stinkbugs typically are roundish in shape and often brightly coloured. They are all wingless though, as is the case for all juvenile Hemipterans.
Below: Newly hatched stinkbugs (likely Plautia fimbriata).
Diet
Most true bugs such as aphids, whiteflies, many stink bugs and leaf-footed bugs suck the sap of plants. There are yet many that are carnivorous in nature, such as assassin bugs and giant water bugs. Some even feed on human blood, such as bed bugs and certain assassin bugs (also known as kissing bugs).
Above: Many Hemipterans feed on plant sap, such as this Ricanula sublimata planthopper.
Relationship with humans
Many Hemipterans get a bad rap for hurting crop yields. Aphids, mealybugs and whiteflies are infamous among farmers and gardeners for being huge pests. Individually, they may not do much harm, but their high fecundity often ensures sizable damage to crops and plants due to the sheer number of insects present. Many of these sap-sucking true bugs are also quite tiny, meaning that they are easily missed by plant growers which results in easy transmission and infestation of the bugs by accidental introduction to plants.
Another negative impact the Hemipterans have on humans is the sucking of human blood. Bed bugs are well-known for haematophagy, but are more of a nuisance than threat, since they are not known to transmit human diseases. The dangerous bugs are the kissing bugs (Triatominae, Reduviidae). These blood-suckers are known to transmit the deadly Chagas disease, caused by the protist Trypanosoma cruzi. This disease kills thousands of people in South America annually, and controlling the vector bug (such as Rhodnius prolixus) is one of the best ways to control the disease.
There are many ways Hemipterans benefit humans too. Many true bugs are predatory, and are commonly used in biological pest control to control a wide range of agricultural pests like aphids, mealybugs and beetles. Assassin bugs (Reduviidae) are notable for this role, as are carnivorous stink bugs (Asopinae, Pentatomidae) and pirate bugs (Anthocoridae).
Notable families
Suborder Heteroptera
1) Pentatomidae (Stink bugs)
One of the more popular families, the Stink bugs are mainly herbivorous, although one subfamily (Asopinae) is entirely carnivorous. They are aptly named because of their stink glands, which produces a nasty odour when the bugs are disturbed. The Pentatomids are also sometimes called shield bugs, because of their trapezoidal body shape. Many species are considered agricultural pests, with the Brown marmorated stink bug (Halyomorpha halys) being one of the more prominent stink bug pests in North America. In Singapore, native species include Banasa dimiata, Eocanthecona furcellata (Predatory Stink Bug) and Palomena prasina (Green Shield Bug).
Above: A common stinkbug species found in Singapore, Plautia fimbriata.
2) Coreidae (Leaf-footed bugs)
The Coreids are entirely phytophagous; many species are considered pests of agriculture. Many species have swollen hind legs (specifically the tibia), thus giving them their common name of leaf-footed bugs. Coreids are known to secrete a foul smelling odour when provoked. While the nymphs of some species are commonly mistaken for the nymphs of carnivorous assassin bugs (Reduviidae), a key difference to look out for is the proboscis. In assassin bugs, the proboscis is shorter and hooked, while the leaf-footed bugs have longer, thread-like proboscis. Local species include Leptoglossus gonagra (Citron bug), Mictis longicornis (Rose Coreid), Cletus trigonus and Acanthocoris scaber.
Above: A nymph of the Rose Coreid, Mictis longicornis.
3) Pyrrhocoridae (Red bugs)
Red bugs are so called because, well, they are red in colour. Also known as cotton stainers because of the discernible stains that they leave on cotton crops (Gossypium spp.), many Pyrrhocorids are considered pests of cotton crops as a result. The majority of species in this family attacks plants, especially those in the order Malvales (includes cotton, Gossypium spp. and Sea Hibiscus, Talipariti tiliaceum). However, there exists carnivorous species too, and those are considered beneficial insects as they feed on other insects, including the herbivorous Pyrrhocorids. In Singapore, some Pyrrhocorids that can be found are Dysdercus decussatus (Cotton stainer bug), Antilochus coquebertii (Carnivorous Pyrrhocorid) and Physopelta gutta.
Above: A Cotton stainer bug (Dysdercus decussatus) on its host plant, the Sea Hibiscus (Talipariti tiliaceum). This bug is incredibly common where its host plant resides, such as the coastal areas of Singapore.
4) Belostomatidae (Giant water bugs)
Fearsome predatory aquatic bugs, the Belostamatids or Giant water bugs are known to deliver a painful bite to anyone who is foolish enough to provoke them. These bugs prey on whatever aquatic animal they can overcome, such as smaller fish, tadpoles and even juvenile water snakes. They are known to play dead in the face of a potential predator, and it is thus advisable to not handle even specimens that are presumably dead (these deceptive bugs are also known to emit an odour while playing dead). Giant water bugs truly are some of the most ferocious insects in the world, and they should be treated with respect as such. In Singapore, the largest species encountered is Lethocerus indicus. Diplonychus rusticus is another species found locally.
5) Nepidae (Water scorpions)
Like the Belostomatids, the Nepidae or waterscorpions are carnivorous freshwater insects. They have a breathing tube which allows them to engage in underwater activities for extended periods of time, with said breathing tube siphoning air from the surface. Singaporean species include Ranatra parmata (Water stickinsect) and Cercotmetus asiaticus.
6) Notonectidae (Backswimmers)
These bizarre aquatic insects swim on the surface of the water with their bottoms up. They are carnivorous, and feed on fish fry, mosquito larvae and other smaller aquatic animals. They are known to bite, although understandably the bites from these comparably small insects are not known to hurt as much as say, the bites from the Belostomatids (Giant water bugs). In Singapore, some local species include Anisops niveus, Enithares metallica and Nychia sappho.
7) Corixidae (Water boatmen)
Corixids reside mainly in still water, and although they somewhat resemble the backswimmers, the two families of aquatic bugs can be differentiated in the field quite easily by their behaviour; the former swims dorsal side up, while the latter swims with its ventral side up as their common names suggest. The water boatmen are, quite uniquely among aquatic Hemipterans, mainly herbivorous and feed on algae and water plants. Predatory Corixids are existential, however. One European species of the closely related family Micronectidae (also called water boatmen; in the same superfamily Corixoidea, as Corixidae), Micronecta scholtzi, is known as the loudest animal in the world relative to body size. The Corixids are actually more abundant species wise in the temperate regions, while the Micronectidae water boatmen seem to be more prevalent in the tropics like Singapore. One Corixid species recorded in Singapore is Agraptacorixa hyalinipennis.
8) Saldidae (Shore bugs)
These minute carnivorous bugs live on sandy shores (surprise surprise) and other wet habitats. They seek out smaller insects that they can overcome. Appearance wise they are oval with large eyes and notable antenna. In Singapore, Pentacora malayensis and Saldoida armata are two native shore bug species.
9) Gerridae (Water striders)
Perhaps the most well-known among the aquatic bugs, water striders inhabit the surface of fresh, marine and brackish water. They are carnivorous, and are drawn to ripples created by struggling prey, which are frequently overwhelmed by a congregation of the elegant-looking bugs. Gerrids that live in ephemeral ponds may fly to a more favourable environment should the ponds start to dry up. The water striders are highly unique in the fact that they are the only bugs known to live in the open ocean (a few species in the genus Halobates). In Singapore, Gerrids encountered include Halobates micans (found in the open ocean), Asclepios annadalei (a mangrove species), Halobates proavus (a coastal species) and Aquarius adelaidis (a freshwater species).
10) Hydrometridae (Water measurers)
These aquatic surface dwellers have an elongated head and body, which makes them distinguishable from the water striders. They are otherwise very similar to the water striders, in that they are carnivorous bugs that spread their weight evenly on the water surface with their hydrophobic feet. Unlike the Gerrids, the water measurers are not found in brackish or marine environments. Hydrometra carinata and Hydrometra orientalis are two species found in Singapore.
11) Miridae (Plant bugs)
Mirid bugs are the most speciose family of Heteropterans. One way they may be distinguished from other families of bugs is to look for the obvious presence of the cuneus, distinct triangular portions of the forewing (hemelytra). Most are plant feeders, but a few are predatory. Many Mirid bugs are considered pests of crops. Singaporean species include Helopeltis theivora (Tea mosquito), Helopeltis antoni, Macrolonius sobrinus (Green T bug) and Hyalopeplus vitripennis.
Above: The Mosquito bug (Helopeltis theivora) is a known pest of tea (Camellia sinensis) and cocoa (Theobroma cacao).
12) Reduviidae (Assassin bugs)
I wrote about the assassin bugs in a previous blog post. The Reduviidae are carnivorous terrestrial bugs that can deliver a painful bite if mishandled. Some (Triatominae, the kissing bugs) feed on the blood of mammals and birds, including humans. A few kissing bugs can transmit the potentially fatal Chagas disease, although that has not been recorded in Singapore. Many are considered beneficial though, as they hunt agricultural pests such as beetles and ants. In Singapore, native Reduviids include Scadra costalis (Millipede assassin bug), Cosmolestes picticeps (Yellow assassin bug), Sastrapada singaporiensis and Gardena melinarthrum.
Above: The commonest assassin bug found in Singapore, Cosmolestes picticeps.
13) Cimicidae (Bed bugs)
These infamous parasites are responsible for much of the costly insect warfare in many urban areas. The bed bugs are actually quite picky when it comes to a host; many species feed on a select few species of host animal. The two main species that feed on humans are Cimex lactularius (Common bed bug) and Cimex hemipterus (Tropical bed bug). In a tropical country like Singapore, one is more likely to encounter C. hemipterus. Unlike the kissing bugs (Reduviidae: Triatominae), the bed bugs are not known to transmit deadly diseases to humans; most are mainly just a nuisance.
14) Tingidae (Lace bugs)
Lace bugs are tiny herbivorous bugs that are mostly host-specific, with a lacy appearance and a dorsoventrally flattened body. Some can bite humans, but their bites are not harmful at all. In Singapore, Ammianus sp. and Ypsotingis sideris are some local Tingids.
Suborder Sternorrhyncha
15) Aphididae (Aphids)
Aphids are notorious agricultural pests that cause severe economical losses each year by feeding on important crops such as beans, citrus and cotton. The adults may be winged or apterous (wingless), depending on the environment. Severe infestations of aphids are common, as they reproduce rapidly and some are even parthenogenetic. Aphids are also infamous for having a symbiotic relationship with many species of ants. The ants protect the aphids from would-be predators such as ladybugs and lacewings in exchange for the excrement (dubbed honeydew) that the aphids produce while feeding on the host plant. The ants may even transfer aphids to more favourable environments like a new host plant. This relationship has further heightened the omnipresence and resilience of aphids. In Singapore, Aphis nerii (Yellow aphid) and Aphis fabae (Legume aphid) are two common species of aphids encountered.
16) Pseudococcidae (Mealybugs)
The mealybugs are yet another ubiquitous agricultural pest in the suborder Sternorrhyncha. These white bugs also form a symbiosis with ants, much like the aphids. The white stuff that cloaks the mealybug is actually wax. Adult males do not feed at all, and wind is a major force of distribution for the nymphs, as the mealybugs are usually considerably less motile than the aphids. In Singapore, Pseudococcids found include Maconellicoccus hirsutus (Hibiscus mealybug, a native species) and Nipaecoccus sp. (found in mangroves).
17) Aleyrodidae (Whiteflies)
Whiteflies are not flies at all, although they are indeed unique among Hemipterans in that their nymphs seem to undergo a pupal stage before emerging as winged adults. In Singapore, whiteflies encountered include Aleurocanthus woglumi (Citrus blackfly), Trialeurodes vaporariorum (Greenhouse whitefly) and Bemisia tabaci (Tobacco whitefly).
18) Psyllidae (Jumping plant lice)
Psyllids are frequently very host specific. They are not known to be huge pests of agriculture compared to the other Sternorrhycha like Aleyrodids and Pseudococcids. One species found in Singapore is Mesohomotoma hibisci.
19) Coccidae (Soft scales)
Often called scale insects, the Coccids are closely related to mealybugs, and are often just as immobile. Several are serious agricultural pests. In Singapore, Pulvinaria psidii (Green shield scale) can be found.
Suborder Auchenorrhyncha
20) Cercopidae (Froghoppers)
Froghoppers are so called because their nymphs secrete a tell-tale foam which protects them from drying out, and deters certain predators. The foam is produced as the nymphs feed on plant sap. Cosmoscarta discrepans is one froghopper species found in Singapore.
21) Cicadidae (Cicadas)
Famous for the 17 year life cycle of the periodic cicada species, most cicadas actually have much shorter life cycles. In tropical rainforests, cicadas are commonly the first animals heard, although they are often difficult to spot due to their cryptic habits. The young live underground and feed on roots, emerging only to metamorphosise into adults. Adults also feed on plant sap. In Singapore, Huechys fusca (Golden Black Cicada) and Purana usnani are some cicadas that can be found.
22) Membracidae (Treehoppers)
Treehoppers are also called thorn bugs because of the projection that protrudes from the animal's thorax. This serves to provide better camouflage from predators as many Membracids do indeed look like plant thorns. They are able to fly or hop to escape if need be. Membracids are sap suckers and some species are considered pests in agriculture. In Singapore, treehoppers that can be found include Oxyrachis tarandus (Cow bug) and Tricentrus fulgidus.
23) Cicadellidae (Leafhoppers)
The leafhoppers are powerful jumpers that are also capable of flight as adults. They are sap suckers with varying colourations, some of which are brightly coloured. Some species transmit plant pathogens much like how mosquitoes transmit human diseases. As such, they may be considered plant pests. In Singapore, Kolla bataviae, Tartessus ferrugineus, Idioscopus nitidulus (Mango leafhopper) and Bothrogonia addita can be found.
Above: This cutie is Kolla bataviae. It can easily be missed due to its green colouration and tiny size.
24) Flatidae (Planthoppers)
Planthoppers are represented by several families. The Flatid bugs have nymphs with waxy filaments, while the adults look like 'tents' with their wings folded. Identification among the family is much harder, often requiring genetic analysis. Flatid hoppers found in Singapore include Salurnis marginella, Lawana conspersa (White moth cicada) and Geisha marginellus.
25) Derbidae (Derbid bugs)
Derbid bugs are pretty bizarre looking bugs that can be easily mistaken for flies. The nymphs feed on fungi, while the adults drink plant sap. Derbe longitudinalis and Zoraida pterophoroides are two species that can be encountered in Singapore.
26) Fulgoridae (Lanternflies)
Some Fulgorid planthoppers have a hollow structure that resembles a trunk or snout. Like all planthoppers, they feed on plant sap. Singaporean species include Penthicodes bimaculata and Pyrops oculatus.
27) Ricaniidae (Planthoppers)
Ricaniids hoppers are some of the commonest and more noticeable (due to their not-tiny size) planthoppers seen in Singapore. Some even have deliberate patterns or semi-clear wings. They may often be misidentified as moths. A personal favourite group of mine! Notable species include Ricanula stigmatica, Ricania marginalis and Ricanula sublimata.
Above: This common but beautiful hopper is Ricanula stigmatica.
28) Issidae (Planthoppers)
Issid planthoppers contain some unique looking hoppers, they may appear spherical in shape. Hemisphaerius sp. can be found in Singapore.