Arxiu d'etiquetes: insect pheromones

Sleep tight, don’t let the bed bugs bite!

Have you ever felt uncomfortable when hearing this expression or feared to find your bed infested with bed bugs? Yes, bed bugs exist. However, good news is that not all insects known as ‘bugs’ sting nor live inside our bed sheets.

What bugs really are? Are all of them harmful? Where can we find them? Find out their diversity through this post, and give up thinking that bugs are dangerous!

Which insects are called ‘bugs’?

When talking about ‘bugs’, people are unconscious about the true diversity of these organisms. Bugs, and more exactly true bugs, belong to the Heteroptera suborder, which includes more than 40,000 species worldwide; in fact, they are the largest group of insects with simple metamorphosis. Their most ancient fossil, Paraknightia magnífica, which was found in Australia, has been dated from the late Permian (260-251 MA).

The Heteroptera belong to the Hemiptera order, inside which we can find other suborders which were formerly classified as a single suborder (‘Homoptera’). Some of the suborders once classified as ‘Homoptera’ include some well-known organisms, such as cicadas (Cicadidae) and aphids (Aphididae).

How can we recognize them?

Heteropterans appear in different forms and sizes. The tiniest specimens belong to the Anthocoridae, Microphysidae, Ceratocombidae, Dipsocoridae, Aepophilidae and Leptopodidae families, which are barely visible to the naked eye. Among the largest members there are some species of the Belostomatidae family, such as Lethocerus indicus (6.5-8 cm length). Despite this, they appear as a monophyletic group according to molecular data.

They show at least three synapomorphies:

  1. Piercing-sucking mouthparts, long, forming a stylet.

    Mouthparts of the predator Arilus cristatus (Reduviidae). Picture property of John Flannery on Flicker (CC 2.0).
  2. Paired odoriferous glands.
  3. Four-segmented antennae.

Furthermore, they have forewings (formally known as hemelytra) with both membranous and hardened portions, which gives its name to the group (Heteroptera, from the Ancient Greek ‘hetero’, different; ‘-pteron’, wings).

Pentatomidae. The proximal part of forewings is hardened, while the distal one is membranous. Picture property of Mick Talbot on Flickr (CC 2.0).


Life cycle

Heteropterans undergo a simple metamorphosis, so youths or nymphs and adults almost show no differences and cohabit in the same habitat. After hatching, nymphs molt several times until reaching the last nymphal molt, known as imaginal molt, through which they reach adulthood.

Life cycle of heteropterans. Picture property of Encyclopedia Britannica, Inc. (link).

Adults differ from nymphs on having wings, a new disposition of odoriferous glands openings, a different number of tarsal (legs) and antennal segments, ocelli, ornaments (spines and glandular hairs), sexual traits on the terminal abdominal segments and sometimes a different coloration, besides a bigger size and a way harder tegument.

Nezara viridula nymph (Pentatomidae), still wingless. Picture property of S. Rae on Flickr (CC 2.0)

Communication and defense

Specimens of the same species emit volatile pheromones produced by their odoriferous glands as a way of communication. So, they can expel aggregation pheromones and sexual pheromones to gather in a point or to find a mate, respectively. In some species, it has also been documented the emission of sounds produced by stridulation, that is, producing sounds by rubbing together certain body parts.

Heteropterans develop passive and active defense mechanisms:

  • Among passive mechanisms, we can highlight the own body shapes (e. g., smooth and rounded structures which difficult their capture by predators), the inactivity as a way to go unnoticed by other organisms, and the crypsis or mimicry. Some examples of crypsis or mimicry are 1) color mimesis (homocromy) 2) shape mimesis (homotopy), through which they imitate structures of their environment, either plants or animals (e. g. ant-mimicry or myrmecomorphy) and 3) disruptive mimesis, that is, their outlines get blurred with the environment, so it gets difficult for predators to find them.
Leptoglossus occidentalis (Coreidae), with their wide tibiae that look like leaves. Picture property of Giancarlodessi (CC 3.0).
Myrmecoris gracilis (Miridae), a clear example of ant-mimicry or myrmecomorphy. Picture property of Michael F. Schönitzer (CC 4.0).
  • Some active mechanisms are 1) escaping, 2) biting, 3) the detachment of some appendices to confuse predators and 4) the emission of stink or irritating substances by their odoriferous glands, which in most of cases they acquire from plants they feed on. Others emit stridulating sounds.

Life forms and diversity

Even though most people know something about heteropterans due to the famous bed bugs, feeding on blood is far from being the only life form among true bugs.

  • Terrestrial

Most heteropterans inhabit terrestrial environments, either on plants or on the ground as phytophagous (they feed on vegetal fluids) or predators of other insects. There are also some terrestrial heteropterans that feed on roots or on fungi that develop under tree bark. Some examples of terrestrial phytophagous families are Pentatomidae and Coreidae. Among predators, which use their stylet to inoculate proteolytic agents inside their preys to dissolve their content and then suck it, there are a lot of members from Reduviidae family.

  • Aquatic and semiaquatic

Aquatic and semiaquatic forms have special adaptations to live in water, like hydrofuge hairpiles which repel the water. Most of them live in lakes and rivers, either on their surface (semiaquatic) or submerged.

Semiaquatic species usually have long legs and long antennae, which together with the hydrofuge hairpiles let them to stand on water. Water striders (Gerridae), which are very abundant in Europe, are a clear example of this life form.

Water striders (Gerris sp.). Picture property of Webrunner (CC 3.0)

Aquatic species usually have a pair of legs adapted to swim. A good example of this are the members of the family Notonectidae or backswimmers, which have the hind legs fringed for swimming.

Notonecta sp. (Notonectidae). Picture property of Jane Burton/Bruce Coleman Ltd. (link).

Despite living in water, aquatic heteropterans need surface air to breath, so they go out of water periodically. They present different strategies to absorb oxygen, such as swallowing air that goes directly to the respiratory or tracheal system through a siphon (Nepidae) or capturing air bubbles with their hydrofuge hairpiles (Nepidae). Other simply get covered of a tiny air layer using their hydrofuge hairpiles.

  • Hematophagous

Finally, there are heteropterans that feed on blood and live as bird and mammal parasites. This is the case of the Cimicidae family (e. g. Cimex lectularius, the bed bug) and some groups of Reduviidae, such as the members of the subfamily Triatominae, which are also known for being vectors of the Chagas disease in the center and south of America (being Triatoma infestans its main vector).

Cimex lectularius or bed bug nymph. Public domain.
Triatoma sp. (Triatominae). Picture property of Bramadi Arya (CC 4.0).

Scientific interest

  • They help to regulate some wood and crop pests, having an important role in integratative pest management. This is the case of some predator heteropterans from the Reduviidae, Anthocoridae, Miridae, Nabidae and Geocoridae families. However, some phytophagous heteropterans can act as pests too.
  • They have been an interesting scientific model for the study of insect physiology.
  • They are an important element on human diet in some countries, being Pentatomidae one of the most consumed families. Some aquatic heteropterans, such as Lethocerus sp. (Belostomatidae) are very appreciated as food in some Asiatic countries, like Vietnam and Thailand.
Lethocerus sp. Picture property of Judy Gallagher on Flickr (CC 2.0).
  • Some of them are disease vectors or a cause of discomfort. The most classic example is the bed bug (Cimex lectularius), which has become a frequent pest in temperate regions; some Cimidae are also a threat for free range chickens and other farm birds. In America, Triatominae are vectors of different diseases, being the most famous the Chagas disease (transmitted by a protozoan, Trypanosoma cruzi).

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All organisms on Earth are necessary for some reason: you only need to investigate about them. Even the true bugs!


Main picture property of Pavel Kirillov on Flickr, with license  Creative Commons 2.0. (link).

How do insects communicate?

How do ants know what path to follow? Which mechanisms do some male and female moths use to meet each other when located far away? As humans along history, insects have developed different ways to communicate with each other.

Do you want to know how and for what purpose do insects communicate by all its senses? Keep reading!

Insects language

Communication is defined as an exchange of information between two (or more) individuals: the one/s that transmits the message (emitter) and the one/s that receives and processes that message. While in humans communication passes through a long learning process, in insects the same process tends to be an inborn mechanism: each newborn individual has an specific vocabulary shared only with organisms of its own species.

On the other hand, we tend to see communication as an obvious process (if the emitter says “Thank you!” we expect the receptor to say “You’re welcome” in return). In insects, likewise in other animals, communication can take place in a way that information can’t be appreciated for us (humans).

Thus, it’s be better to say that communication is an act or condition of any part of an organism that alters the behavior of another organism. What does it means? That the emitter insect sends a missage to the rest of organisms by doing some action (e.g. an acoustic signal) or maybe by developing some physical trait which informs the rest of individual of some stuff (e.g. the color pattern of wings of some butterflies), in order to induce some answer or changes on the receptors that would benefit one or both of them.

Why do insects communicate?

Insects communicate both with organisms of the same species (intraspecific communication) and directly or indirectly with organisms of other species (interspecific communication) for many reasons:

  • Reproduction: to look for a mate, courtship…
  • To identify members of the same species or even to warn other organisms of its own presence.
  • To localize sources of recourses : food, nidification places,…
  • As an alert signal towards potential hazards.
  • To defend territory.
  • As a way to camouflage or to mimic other organisms (Do you want to learn more about animal mimicry? click here!).

Language through senses

Insects use almost all senses to communicate. Along this section, we’ll analyze one by one all communication systems that insects developed through the “five sense”, just like some of the flashiest examples.

Tactile communication: “The touch”

Tactile communication in insects would be equivalent to the sense of touch in vertebrates. Although nervous system in insects is underdeveloped compared to the one of vertebrates, tactile communication is based on the same principle: it must be some type of direct or indirect physical contact between the emitter of the message and the receptor.

  • “Tandem running”: Follow the leader!

Since long ago, we know that ants walk in line one after another because some of them leave a chemical track that the rest of individuals follow to not get lost. But, aside of emitting these chemical signals, some ant species seem to establish an strategic physical contact system known as tandem running: the ant located behind touches the abdomen of the one that is immediately before it (the leader) with its antennae; moreover, if the leader stops feeling the antennae of the one behind, the leader will turn and wait for the one that follows it.

tandem running
“Tandem running” steps observed in ants (it has also been studied in some termites species). Image source: link.

This video from Stephen Pratt Youtube channel shows two ants performing this kind of contact known as “tandem running”:

  • Dancing bees

Honey bees (Apis mellifera) perform dances to show other members of their colonies where nectar is located (direction and distance) and also if it has a high quality. Bees dance inside their hives, so this performance takes place in deep darkness. So, you’ll ask yourself: why dance if no one sees you? Because the sense of sight is not necessary in this case to transmit the information: the rest of bees don’t perceive the movements in essence, but only the vibrations the dancing bee transmits trough all the hive will moving.

Look at these dancing bees! (video from Ilse Knatz Ortabasi Youtube channel):

Chemical communication: “smell and taste” 

Chemical communication is probably the most extended communication mechanism among insects. In this type of communication, the emitter scatters chemical substances at the environment which are detected by other organisms. There exists a lot of types of chemical substances: pheromones (for finding a mate), allelochemicals (as alarm signals, as a defensive system…), etc.

Even more important than how they scatter those substances, is the system they use to detect them: insects have more or less specialized receptors located on their antennae, their legs, etc. We can say they can savor and smell these substances with almost all parts of their body!

  • Love gives you wings…and pheromones!

Females of some moth species emit pheromones that can be detected even by male moth located kilometers away. This is the case of Small Emperor Moth females (Saturnia pavonia), which attract males located almost 16km away.

Saturnia pavonia male (above) and female (below). Picture by Stephen Dalton ©.
  • Your smell betrays you!

Communication can take place among insects of the same or different species. Euclytia flava is a bedbug parasitoid (learn more about parasitoids here) that detects its hosts by the way they smell: more accurately, by detecting the chemical substances that the hosts emit (these type of substances that benefit the receptor but not the emitter are known as kairomones).

Euclytia flava (Copyright © 2013 Christopher Adam).

Auditory communication: “the hearing” 

Insects emit a wide variety of sounds in different frequencies, amplitude and periodicity, and each species has a very well defined pattern. In fact, only by registering and analyzing insect’s sounds we can identify the species that has emitted them.

While humans can detect sounds in a range from 20 to 20.000Hz, insects can emit and detect sounds above this range (some crickets can produce ultrasounds above 80.000Hz).

  • The summer sound

Cicades are amazing for many reasons: they remain more than 17 years in a nymph state underground until they reach adulthood and also emit a wide range of singings from sunrise to sunset during summer months. They emit these sound by stridulatory organs located in the abdomen, and are received by an auditory organs located on their legs or thorax.

Listen to this cicade singing! (Dangerous insects planet Youtube channel). Can see how its abdomen vibrates?

Some cicades are able to emit sounds that exceeds 120 decibels (they almost reach the human ear pain threshold!). However, some small cicade species emit sounds in a so elevated frequency that can’t be listened by humans, but that could be painful for other animals.

The sounds of cicades have many purposes, although they use it specially for finding a mate or to delimitate their territory.

  • “I’m all antennae”

Some studies reinforce the idea that males of some mosquitoes species have a higher sensibility in their antennae to detect the vibrations emitted by the beating of female wings through the air.

Electron microscopy image of a male mosquito in which we can appreciate its feathery antennae; these pilosities heighten its sensibility (This image has been taken with EVO® MA10; picture by ZEISS Microscopy, CC).

Visual communication: “The sight”

Visual communication in insects takes place by two main systems: body color patterns and light signals (bioluminescence).

Each species has specific color patterns, which can be useful for identifying members of the same species, also to attract a mate o even to alert other organisms about its dangerousness (aposematic mimicry; learn more about it here), or to drive away predators. On the other hand, there are also species that emit light signals to attract other specimens (e.g. fireflies or beetle from Lampyridae family).

  • Eyes…or only spots?
Caligo memnon
Caligo memnon, with its spots that resemble two big owl eyes and witch allow them to drive away predators (Picture by Edwin Dalorzo, CC).
  • Lights in the dark

Fireflies are the most common example of communication mediated by bioluminescent signals, but there exist more insects which are able to emit light:

The click beetle (Pyrophorus Noctilucus) has two small bioluminescent organs located behind its head. The light of these organs get more intense when being menaced (Image source:
oruga luz
Larvae or larviform adult females from the beetle genus Phrixothrix emit two types of light: green and red. They emit red light by two organs located in their heads only when they feel menaced in order to alert other larvae about the presence of predators (image source:

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As you see, insects communicate in some different ways. Do you dare to discover how do insects that live near you communicate?


  • Gopfert M.C; Briegel H; Robert D. (1999). Mosquito Hearing: Sound-Induced Antennal Vibrations in Male and Female Aedes Aegypti. The Journal of Experimental Biology. 202: 2727-2738.
  • J.R. Aldrich, A. Zhang (2002). Kairomone strains of Euclytia flava (Townsend), a parasitoid of stink bugs. Journal of Chemical Ecology, Volume 28, Issue 8, pp 1565-1582.
  • Nigel R. Franks, Tom Richardson (2006). Teaching in tandem-running ants. Nature 439, 153.
  • Insectos: la mejor guía de bichos. Parragon Books Ltd.
  • insect communications

Main image by Radim Shreider © (National Geographic Photo Contest 2012).