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Emotional Inse cts

Even insects express ang er,

terror, jea lousy and love.

– Charles Darwin

Contents W h a t Ma ke s Us Hum a n ?


Parental Care












Tr u s t



W h a t M a k e s Us H u m a n ?

The Oxford Dictionary’s definition of emotion is;

A natural instinctive state of mind d e r i v i n g f r o m o n e ’s circumstances, mood, or relationships with others.

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This book is a dedication to the grotesque, gruesome, ugly yet beautiful things we call insects. They are an essential part of our eco system and no matter how squeamish we are of them we can’t escape the fact that we need them. This book conveys the similarities amongst insects and us. A collection of insects’ emotional characteristics, that may not be a replica of human interactions but are essentially an essence of what makes us human. We consider emotions to be a special quality specific to humans, but if emotion is defined by an ‘instinctive state of mind’ surely all creatures have instincts? This theory was created by Charles Darwin, this collection of insect behaviour was inspired by his theories and books ‘The Expression of the Emotions in Man and Animals’ and ‘The Origin of Species’.


Parental Care

People often describe the makeup of their personalities and what defines them as being a reflection of their parents. Many species have parents but insects you would think would object to this notion, but it’s a tough world out there for insects and parents have got to do what they can to protect their genetic material. It doesn’t sound particularly sentimental but the parental care of some insects is more than just fighting off predators. The simplest form of insect parental care is for the females to lay their eggs in or on the food, this is the case with butterflies, moths, beetles and many flies.

Egg Guarding More active parental care involves the mother remaining with the eggs until they hatch and can fend for themselves. The shieldbug, Elasmucha grisea, remains with her egg batch on a birch leaf until they hatch. She protects them against predatory insects. In terms of egg guarding the females are most often involved.

Paterna l D a d s The females of belosomatid water bugs lay their eggs on the backs of their mates. The males carry them around until they hatch. This is one of the few examples of when the male of the insect takes care of the eggs, he carries the little ones on his back to keep them from harm.



O verprotective Mothers The tropical fungus beetle, Pselaphicus giganteus, inhabits central American forests and some Caribbean islands. Unlike most beetles the females of this species remains with her young to ensure their safety and well being. A female Pselaphicus giganteus lays her eggs on a fallen log, she remains with them, guarding them from danger. She is brightly coloured, suggesting that she is poisonous or at least highly distasteful.



A beetle is a beauty in the eyes of his mother



When the eggs hatch into larvae the mother shepards them to their first fungus meal. When they have eaten their fill on one fungus the female guides the larvae to another log. As she does so, she drags the tip of her abdomen along the log surface with side to side movements, she lays a scent trail for her children to follow. She is a very attentive mother, constantly fussing around her larvae, touching them with her antennae and running about to round up stragglers. The larvae stage lasts only four days before pupation. The mother is constrantly there throughout the larvae stage keeping them safe.








The honey bee colony is the best understood example of cooperative group functioning outside the realm of human society




The D a nc e o f the Hone y B e e For a food source greater than 100m from the hive a returned forager performs the waggle dance. This is a flattened figure of eight, she waggles her abdomen very rapidly from side to side and buzzes rapidly. The number of waggles in the dance indicate the distance of the food source from the hive. The tempo of the dance and the number of times she repeats it, together with the high frequency buzzes of 250mhz are indications of the quality of the food in terms of calorific reward. The waggle dance also conveys distance and direction. The angle of the dance corresponds to the angle between the sun as seen from the hive entrance and the direction of the food source. The bee is able to impart accurate directional information because she has memorised the position of the sun on her return journey. Her sense of time enables her to compensate for the suns changing position. The third dance is called the vibration dance: workers vibrate their bodies rapidly in an up and down direction. This dance directs workers to area where waggle dances are being performed. Vibration dances are most frequent at times when the colony needs more food.

Honey bees live in colonies and serve their queens. There is one queen per colony and they have ten times the lifespan of worker bees. There are tens of thousands of worker bees per colony, they have been found to display sophisticated cognitive abilities. They communicate new food discoveries with a ‘dance language’, originally deciphered by Karl Von Frisch who was an Austrian ethologist. The honey bees ‘dance language’ is the only non-primate symbolic language. Recent studies have revealed that honeybees can learn concepts such as ‘same’ and ‘different’. The ‘dance language’ is made up of three types of dance moves; round, waggle and vibration. A forager bee will return from a food source within 25 m of the hive and perform a round dance. This is made up of circular motions with regular changes of direction. A dancing worker attracts and holds the attention of a group of worker bees called followers. They constantly touch her with their antennae and taste the nectar she regurgitates. The frequency of direction that changes in the round dance indicates the quality of the food.


The dance language of the honeybee is remarkably complex behaviour. It involves the bee remembering visual, directional and calorific data and being able to pass it on to their fellow bees by using a system of stereotyped, coded signals, each of which has meaning; together these signals impart a real message, full of information.

For this to work, the other bees must be able to perceive, understand and translate this information into a rewarding foraging trip. Our language conveys information via sounds and written marks which have agreed symbolic meanings. The dance language of honeybees is a multichannel system of communication that uses coded signals full of meaning.

“ It i s th er e f o r e a true language in the same sense as our own.

� 21

Thrill-seeking Bees When a colony outgrows its living quarters, the swarm must hunt for a new home. Around five percent of the swarm goes hunting for a new home. Researchers discovered that these “nest scouts” are more likely than their peers to also become food scouts. In order to understand the molecular basis for these differences, Robinson and his colleagues used whole-genome microarray analysis to look for differences in the activity of thousands of genes in the brains of the thrill-seeking and non thrillseeking bees. They found thousands of differences in gene activity. “Our results say that noveltyseeking in humans and other vertebrates has parallels in an insect. One can see the same sort of consistent behavioural differences and molecular underpinnings,” said Robinson. Robinson believes that insects, humans and other animals have made use of the same genetic “toolkit” in the evolution of behaviour, which each species has adapted. “It looks like the same molecular pathways have been engaged repeatedly in evolution to give rise to individual differences in novelty-seeking,” he concluded.

According to a study by entomologists at the University of Illinois bees have can have different “personalities” with some showing a stronger desire to seek adventure than others. The researchers found that thrill-seeking is not limited to humans. The brains of honeybees that were more likely than others to seek adventure exhibited distinct patterns of gene activity similar to the patterns in thrill-seeking in humans. The findings at Illinois University present a new perspective on honeybee communities. Previously the hive was thought to be highly organized and made up of workers taking on a specific roles to serve their queen. It now seems as though individual honeybees differ in their desire to perform particular tasks and these differences could be down to variability in bees’ personalities. This supports a 2011 study at Newcastle University that suggested that honeybees exhibit pessimism, suggesting that insects might have feelings. Gene Robinson, entomology professor and director of the Institute for Genomic Biology, said: “In humans, differences in noveltyseeking are a component of personality. Could insects also have personalities?” Robinson and his team studies two behaviours that looked like novelty-seeking: scouting for new nest sites and scouting for food.








Corpse Gifts Males of the common European scorpionfly, Panorpa communis, have two principal ways of offering a gift to their mate. A male seeks an insect corpse as a gift – often this will be stolen from a spider’s web. He then settles down next to his gift and emits a sex pheromone which attracts a female. She eats the gift while the male mates with her. If he cannot find a suitable insect corpse, he adopts another ploy. He deposits a drop of rapidly drying saliva on a leaf and moulds into a pillar shape. He sits by his spit and then again calls to passing females with his pheromone. A female can assess the fitness of her potential mate by the amount of saliva offered.


Pa rents At Funer a ls Nicrophorus americanus is a nocturnal beetle and is a strong flier, moving as far as a kilometre in one night. During the winter months when temperatures are particularly low americanus adults bury themselves in the soil over winter. When temperatures increase they emerge from the soil and begin the mating process. Burying beetles are unusual in that both the male and female take part in raising the young. Male burying beetles often locate carcasses first and then attract a mate. Beetles often fight over the carcass, with usually the largest male and female individuals winning. The victors bury the carcass, the pair mate, and the female lays her eggs in an adjacent tunnel. Within a few days, the larvae develop and both parents feed and tend their young, an unusual activity among insects.


The larvae spend about a week feeding off of the carcass then crawl into the soil to develop. Mature Nicrophorus americanus beetles emerge from the soil around 45 to 60 days after their parents initially bury the carcass. Adult American burying beetles only live for twelve months. Both larvae and adults of Necrophorus feed on carrion. The adults can detect a rotting corpse from a large distance. Usually a Necrophorus defends its carcass against members of the same sex, but a single mated pair co-operate in burying the corpse. In some species, four or five females may collaborate and bury a dead mouse as it is quicker than one beetle working alone. In this situation one female becomes dominant and she lays her eggs on the buried mouse. Burying beetles can detect corpses which have already been buried by other beetles. They will kill any young larvae they find there and lay their own eggs in place. For this reason it pays for parents to remain with their young larvae and protect them.


“ What would be left of our tragedies if a insect were to present us his ?

� -Emile M Cioran






A g g r e ss i v e Po s t ur e Praying mantises use a threatening display in which they rear up and show off their spiny raptorial legs in an aggressive posture. Parasphendale mantis species are a very aggressive, the female is especially known for its voracity. She actively chases after her prey once she is aware of it. When threatened the Parasphendale mantis will reveal bright colours on the forearms, and hold them out beside their head in a way that will scare predators. The females of this species are larger and wider than the males, this can already be seen when they are still a nymph. Females are large with short wings, while males are small and slender and with long wings.

Approximately 2 to 4 weeks after the mantis sheds its skin, the male and female can be introduced for mating purposes. The female must be well fed before introducing the male to her enclosure as the female can be quite aggressive to the male and will most likely eat him before the mating. Mating can take several hours, the male must subsequently be removed from the residence.

Dangerous Saliva The body fluids of some beetles are extremely toxic. Various beetles provide a literally explosive experience for predators foolish enough to tackle them. These are the famous bombardier ground beetles found in North America and Europe. When attacked the beetle releases a jet of p-benzoquinone from the anus at a temperature of 100 degrees celsius. This chemical is highly repugnant to spiders, predatory insects, rodents and birds. The release is accompanied by an audible pop, like the crackle of gun fire. The beetles have a highly mobile tip to the abdomen, so they can direct their line of fire at the predator. P-benzoquinon is volatile and unstable so beetles cannot store it; instead they manufacture it explosively on demand. Paired glands synthesize peroxide and quinones to create the toxic body fluid. When attacked the beetle discharges the mixture into a combustion chamber with a one way valve. This chamber contains oxidizing enzymes, which catalyse the explosive formation of p-benzoquinone. The force of the explosion closes the one-way valve and in this way the chemical spray is forcibly discharged through the anus.


“ Bugs are not going to inherit the earth. T h e y o w n i t n o w.

� - John H. Lienhard


Species of the genus Phymateus are African locusts that raise and rustle their wings when disturbed and secrete a noxious fluid from the thoracic joint. These locusts feed on highly toxic plants and usually congregate in large numbers on trees and shrubs, arranged in such a way as to resemble foliage. Females of the species are unable to fly, despite fully having developed wings.







Before mating, each insect has to be able to recognize the opposite sex of its own species. The sheer number of insects at any one area makes this a daunting task: on average there are 10 billion insects per square kilometre. Many of these will be closely related species. For this reason insects have evolved many intricate and elegant ways of mate recognition through a variety of different techniques. These may involve specific scents, sounds, semaphore signals, and pulses of flashing lights.

S i l k Wr a p p e d G i f t s The males of Hilara species wrap a gift to their female potential mates in a balloon of silk. Deception is common, with inedible objects such as petals or seeds being gift-wrapped rather than a genuine gift of an insect. Sometimes a male dispenses with a gift all together and simply offers an empty balloon of silk. Male and some female insects advertise their readiness to mate in a variety of ways. What ever signals are used the message must be clear and unequivocal: it must identify the species of the calling individual.

“ Green little vaulter in the sunny grass, catching your heart up in the f e el o f June.

” – To the Grasshopper and the Cricket By James Henry Leigh Hunt

Sexual Communication In North America, there are fireflies which generate flashing lights for sexual communication. The males of these Photinus fireflies emit pulses of light. The frequency and duration are unique to the species; the females of each species answer in their own characteristic pattern. In this way, the sexes find each other and mate. Males are the first to start the series of patrolling flashes needed to locate and mate with a female. Males will actively fly while flashing, whereas females are sedentary. They will flash every 6 seconds and wait for a responding flash from the female. It has been shown that females only respond to males of their species; identifying them by the colour of their yellow bioluminescent flash. Females will twist their abdomen towards the males flash, presenting their own flash toward the male. The males show an obvious gaze shift towards the last female flash, and continue towards it until the female firefly flashes again. The flashes continue until the male reaches the female.

Love Songs Male grasshoppers generate their love songs by stridulation, this is rubbing a row of tiny pegs on the inner sides of the hind legs against an especially hardened vein on the forewing. The spacing and size of the pegs contribute to the uniqueness of the species song.


Ve n t r i l o q u i s t s The song of certain male cicadas is the loudest of all noises created within the animal kingdom. These bugs have a remarkable structure for generating sound by using a tymbal which is located at each side of the abdomen. The tymbals are regions of the exoskeleton that have complex membranes that vibrate rapidly. The cicada’s body has enlarged chambers that resonate to greatly amplifying the sound. Each species has its own characteristic song. Cicadas are superb ventriloquists. This makes it impossible for the vertebrate ear to locate the position of a calling male. Therefore while a male cicada is broadcasting his presence loud and clear, predators cannot locate his exact position. Only a receptive female, ready and willing to mate can locate him.


“ Even a one - inch insect has a half-inch soul.

� - Japanese Proverb






Batesian Mimicr y

Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a common predator. The warning colours of the butterfly, Acraea macaria hemileuca (Kenya) indicate that it is a poisonous species. It is a model for a non-toxic species the swallowtail butterfly, Papilio jacksoni which mimics the Acraea. When a non-toxic species mimics the warning colour pattern of a toxic species this is called batesian mimicry. The oil beetle, Mylabris oculata which can be found in South Africa, is chemically protected by the presence of a powerful poison in the wing cases. The markings are a warning to would be predators, but this signal is subverted by this jewel beetle, Agelia petali which is the batesian mimic of the oil beetle.





Tr u s t



Chatty Ants Ants produce ten of twenty different chemicals to signal specific requests and warnings, passing them through physical contact or leaving them behind as chemical trails. Complex tasks can be carried out through a simple reinforcement system. Weaver ants, for example, join together to bend two leaves to gather and glue them in place, the decision to pick a particular leaf for this team effort is set decided by a single worker; if the ant succeeds in bending a leaf, it releases a ‘success’ pheromone, which recruits another to the task. Antennal communication, using the sense of touch and especially that of smell, is crucial to ants’ organized behaviour.

Ant colonies are often made up of two million or more members. Coordinating the functions of the nest requires a reliable system of communication. To find and retrieve food with maximum efficiency foragers need to be able to recruit their fellow workers to good sources. They must be able to recognize their own nest mates and distinguish them from potentially hostile foreigners. If enemies are detected they need to be able to signal their presence to their own kind, recruiting some to the battle and others to the task of savaging eggs, larvae and pupae. All these tasks are completed through chemical communication called pheromones.


“ There are no species of ant that live independently



Bibliography Charlotte Sleigh (2004). Ant. Reaktion Books. Christopher O’Toole (1995). Alien empire: an exploration of the lives of insects. Harper Collins. Jae C. Choe, Bernard J. Crespi (1997). The Evolution of Social Behaviour in Insects and Arachnids. Cambridge University Press. Olivia Solon. (2012). Honeybees May Have Personality. Available:

By Holly Dennis 63


There are 200 million insects


to every human being

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emotional insects