What is Insect: Definition and 48 Discussions

Insects or Insecta (from Latin insectum) are pancrustacean hexapod invertebrates and the largest group within the arthropod phylum. Definitions and circumscriptions vary; usually, insects comprise a class within the Arthropoda. As used here, the term Insecta is synonymous with Ectognatha. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms. The total number of extant species is estimated at between six and ten million; potentially over 90% of the animal life forms on Earth are insects. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, which are dominated by another arthropod group, crustaceans, which recent research has indicated insects are nested within.
Nearly all insects hatch from eggs. Insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages often differ from the adults in structure, habit and habitat, and can include a passive pupal stage in those groups that undergo four-stage metamorphosis. Insects that undergo three-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the insects is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm (22 to 28 in). The most diverse insect groups appear to have coevolved with flowering plants.
Adult insects typically move about by walking, flying, or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles, composed of the front and rear on one side with the middle on the other side. Insects are the only invertebrates to have evolved flight, and all flying insects derive from one common ancestor. Many insects spend at least part of their lives under water, with larval adaptations that include gills, and some adult insects are aquatic and have adaptations for swimming. Some species, such as water striders, are capable of walking on the surface of water. Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs and young. Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyrid beetles communicate with light.
Humans regard certain insects as pests, and attempt to control them using insecticides, and a host of other techniques. Some insects damage crops by feeding on sap, leaves, fruits, or wood. Some species are parasitic, and may vector diseases. Some insects perform complex ecological roles; blow-flies, for example, help consume carrion but also spread diseases. Insect pollinators are essential to the life cycle of many flowering plant species on which most organisms, including humans, are at least partly dependent; without them, the terrestrial portion of the biosphere would be devastated. Many insects are considered ecologically beneficial as predators and a few provide direct economic benefit. Silkworms produce silk and honey bees produce honey and both have been domesticated by humans. Insects are consumed as food in 80% of the world's nations, by people in roughly 3000 ethnic groups. Human activities also have effects on insect biodiversity.

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  1. C

    How does one check life signs of an insect?

    Suppose some insect is squashed, let's consider a spider for example; suppose it doesn't move and doesn't react to external stimuli but is still alive; the observer doesn't know this and he wants to determine for sure if the spider is still alive. How does he do this?
  2. BillTre

    Aerodynamics of Insect Flight

    I am putting this in General Discussion because it could go into either biology or aerodynamics. Remember how bumble bees were not supposed to be able to fly aerodynamically? This explains why that is wrong. Here is a podcast I just found (came out in 2019). The two podcast guys interview...
  3. BillTre

    Exploring Insect Vision: Muscles Behind Compound Eyes

    Here's something different: I just heard a podcast about recent biological research. Fly are insects (arhtropods) with an exoskeleton. An exoskeleton cuticle covers are the exposed surface areas of their equivalent of skin cells. The cuticle is usually stiff and hard (to resist mechanical...
  4. Dishsoap

    I Can a microscopic insect fly by flapping rigid wings?

    While in quarantine, I've been reading a lot about some millimeter-scale flying robots, like DARPA's Nano Hummingbird and others. I'm noticing that a lot of millimeter-scale flying robots flap their wings like a fly, and I'm wondering if it's even possible to use this motion to move if the fly...
  5. Knowledge Seeker

    Senses Necessary for Insect Flight

    Which senses (hearing, seeing and so on) would be necessary to accomplish what flying insects do?
  6. E

    Living gears in the insect Issus Coleoptratus

    There is an insect called the Issus Coleoptratus that has biological mechanical gears that is uses to use its legs.
  7. B

    What species does this insect belong to?

    I just found this insect and I don't know what is it. It seems to be the larva of a fly or maybe a little butterfly. I live in Spain so it is fall. What should I do with it?
  8. jim mcnamara

    Insect, arthropod, and insectivore population crash

    Popular science version: (Let me know if the link has problems) https://www.washingtonpost.com/science/2018/10/15/hyperalarming-study-shows-massive-insect-loss/?utm_term=.f9b8006df72b Long term sampling from the 1970's to 2017/2018 shows losses of insect, arthropod, and insectivore populations...
  9. S

    Nerve cells - insect vs human

    It's easy to find descriptions of how the nervous systems of species differ in the organization of nerves, but are there any important differences in the individual cells? For example, are the individual nerve cells of insects similar to individual nerve cells of humans?
  10. srm

    Calculation of the weight of an insect floating by surface tension

    Homework Statement The surface of a liquid is just able to support the weight of a six-legged insect. The leg ends can be assumed to be spheres each of radius 3.2 × 10−5 m and the weight of the insect is distributed equally over the six legs. The coefficient of surface tension in this case is...
  11. DaveC426913

    Can an anti-itch cream treat secondary itching caused by insect bites?

    This is an academic question - out of curiosity - not so much about actually getting relief. I've got a nasty mosquito bite on the under side of my forearm. It's a Muskoka mosquito - the big ones with the really itchy bites. Even if I don't scratch it, it still rubs on everything from desk...
  12. Ahmed Abdullah

    Insect that has evolved to recognize carnivorous plants

    Obviously in a biome consisting of high density of carnivorous plants any insect that can recognize these plants or at least recognize organs associated with carnivory will get fitness advantage. So it seems a very natural thing to evolve from insects point of view. Has it happenned? If yes...
  13. Termite World

    Termite World

    Sir David Attenborough wonders into the wonderful world of the termites in South Africa to better understand the ways in which these amazing animals ventilate their homes, breed, and fight for survival. Brilliant video from BBC insect and wildlife show 'Life in the Undergrowth'.
  14. Life of Insects

    Life of Insects

    In this remarkable BBC footage, Sir David Attenborough reveals the world of insects such as ants, stick insects, beetles and digger bees.
  15. SDewan

    B An insect flying at 150 km/hr

    Given a scenario, where a car is going at a speed of 150 km/hr on a straight and level road. There is an insect flying inside the car. To a person inside the car, (I really do not know how to say this, but I hope you understand), the insect is flying naturally, basically, the speed of the car...
  16. Stephanus

    Ant Reproduction Without Queen: Possible?

    Dear PF Forum, Can ants reproduce without their ant queen? Supposed I trap some ants, perhaps tens to 1 hundred. And I keep them in a box, ventilated with some food - candy; chocolate; Will they reproduce, considering in 1 hundred ants, not all of them will be all males or all females. Or they...
  17. Pyrus

    Why moths do not get attracted to Sun....

    Moths do get attracted to artificial lights but the do not all go toward sun as sun also produces enormous light. So they would have gone toward sun.. And why do they get attracted toward lights...
  18. Z

    Insect climbing edge of disk

    Homework Statement (Important disclaimer: I came up with this problem out of curiosity in a classical mechanics course, so it might not be in a textbook, in the right place, or even solvable for that matter. However, I feel like it should be solvable, and most likely with elementary methods...
  19. E

    Identifying an Intriguing Insect: A Park Bike Ride Discovery

    I've been riding my bike in the park and I've noticed this guy passing by. It was of a hand palm size. Intriguing. Can you help me identify the insect?
  20. S

    The time span for which insect can see its image?

    1. The problem: A plane mirror of length 2m is kept along the line y=-x as shown in the figure. An insect having velocity of 4 cm/s is moving along x-axis from far away. The time span for which the insect can see its image will be:A)50 sec B)25 sec C)25√2 sec D)50√2 sec 2.The answer...
  21. S

    How much oxygen absorbing area does an insect have?

    Homework Statement Insects don't need lungs. They breath through their skins. In this way they can get enough oxygen to fuel the basic metabolism that is common to all life. Approximate an insect by a cylinder of diameter 4mm and length 5mm. Assuming that the density of the insect is...
  22. Patzee

    How Often Are Insect Fossils Found in Amber?

    How common is it to find fossilized insects entombed in Amber? I ask because there is a jewelry vendor here in Maui who claims that her amber jewelry encapsulating a variety of insects were created naturally, mined in the Baltic area and are thousands of years old. She sure has a lot of these...
  23. Monique

    Insect eggs or droppings of some kind?

    Insect eggs, cocoons, or droppings of some kind? All over my terrace I am finding strange grey balls, does anyone have a clue what they could be? They're about the size of a rolled up pillbug, smooth surface with a matt gloss. I've never seen them before, maybe some nice bug is inside or...
  24. O

    MHB Investigating Long-Term Effects of Insect Poisioning on Bat Populations

    I am given X^= ax -bxy-mx^2-p Y^=cxy-dy The insect population is measured in tons and the bat population in hundredss. The term -p reflects poisoning by farmers. The IVP are x(0) =40 and y(0)=1 the question is whether the poisinoning of the insects serves a purpose in the long run. I let p=0...
  25. Pythagorean

    Insect uses mechanical gears to coordinate jumping

    Insect uses mechanical "gears" to coordinate jumping journalist report: http://www.csmonitor.com/Science/2013/0912/Insect-uses-gears-to-jump-study-finds scientific report: http://www.sciencemag.org/content/341/6151/1254
  26. karush

    MHB -aux.20.The lifespan of a particular species of insect is normally distributed

    1149 The lifespan of a particular species of insect is normally distributed with a mean of $57$ hours and a standard deviation of $4.4$ hours. $90\%$ of the insects die after $t$ hours. Represent this information on a standard normal curve diagram, indicating clearly the area representing...
  27. karush

    MHB -aux04 Species of insect is normally distributed

    just seeing how I did on this one:confused: The lifespan of a particular species of insect is normally distributed with a mean of $57$ hours and a standard deviation of $4.4$ hours. this is the normal distribution with $\mu = 57$ and $\sigma = 4.4$ tried to standardize this by...
  28. C

    Tension in legs of an insect dangling upside down

    Homework Statement Some insects can walk below a thin rod (such as a twig) by hanging from it. Suppose that such an insect has mass m and hangs from a horizontal rod as shown in Fig. 5-35, with angle θ = 40°. Its six legs are all under the same tension, and the leg sections nearest the body...
  29. A

    Insect wing physics? Average force?

    Homework Statement A typical flying insect applies an average force equal to twice its weight during each downward stroke while hovering. Take the mass of the insect to be 10 g, and assume the wings move an average downward distance of 1.0 cm during each stroke Assuming 100 downward strokes...
  30. L

    Insect on spinning record problem

    Homework Statement In an old record player, the flat round vinyl disc (record) is placed on a turntable which spins around. Once it gets going around and around, it moves so that the number of revolutions it makes per minute is constant (33 and 1/3). An insect settles on the edge of the...
  31. R

    What is the angular speed of the insect?

    Homework Statement ok this is a little silly. An apparatus of the figure below is designed to study insects at an acceleration of magnitude 910 m/s2 (= 93g). The apparatus consists of a 2.0-m rod with insect containers at either end. The rod rotates about an axis perpendicular to the rod...
  32. D

    A question about the motion of a flying insect inside a moving vehicle

    I have a very basic question that I have not yet found the answer to. Basically it's this: if you are traveling in a vehicle at 60 mph, what is it that allows a flying insect inside the vehicle to fly around? Is the insect traveling at 60 mph plus or minus its own speed depending on the...
  33. K

    A bat and an insect Doppler's Effect problem.

    The problems in this set of problems that I am doing are generally hard (at least to me). Here's the 5th question which I'm not sure whether or not it IS that simple or just deceptively simple. Horseshoe bats emit sounds from their nostrils and then listen to the frequency of the sound...
  34. Saladsamurai

    Anyone know what kind of insect this is?

    We have heard that the http://www.uvm.edu/albeetle/faq.html#2" is invading the Massachusetts area. I don't think that this is one since it does not look like the one in the photo; but I want to rule out the possibility of it being a relative. Any ideas on what this is?
  35. slider142

    Insect Identification: ID a 3-4cm Long Insect

    We were walking down a Brooklyn sidewalk the other day under several trees when we spotted this insect lying motionless (except when the wind blew, it moved its legs a little to rotate itself). We didn't get too close, as it looked like it could give a bad sting. It has two pairs of long veined...
  36. M

    Insect Wings: Modeling the Complexity of Flight

    Hi everyone! I have a question for you :) I am wondering, if there already is a developed model, imitating insect wings, e.g. bee wings. If you happen to observe them, they seem to be much more complex, but also much more useful and allow a more flexible movement. Insects fly with them not...
  37. M

    Max. Height Insect Can Crawl in a Bowl: u & r

    Homework Statement If the coefficient of friction between an insect and bowl surface is u (mu) and the radius of bowl is r, what is the max height upto which the insect can crawl in the bowl? a) r/root(1 + u2) b) r [ 1 - 1/root(1 + u2)] c) r [root(1 + u2)] d)r [ root(1 + u2) -1 ]...
  38. A

    Help Needed: Troubleshooting a Stream Insect Motion Problem

    I've been having difficulty with this problem and can't seem to find where to start. Any help would really be appreciated. A water insect maintains an average position on the surface of a stream by darting upstream (against the current) then drifting downstream (with the current) to its...
  39. daniel_i_l

    Insect Legs: How Do They Work?

    How do insect legs work? Especially the really small ones that are thinner than human hair? Are they moved by muscles just like peoples? Thanks.
  40. K

    Insects Surviving After Head Removal

    How is it possible for insects to survive after they've had their head removed?
  41. G

    Groundspeed/Airspeed of insect

    Hi all, I am involved in a project to fly small moths down a wind tunnel to measure their flight patterns. the moths fly a total of 1.15m into a headwind of 1m/s. i am currently using velocity=distance/time to calculate an average speed but am unsure if this would be a called a...
  42. D

    Identifying Mysterious Insect in Bedroom

    Just now, i found a flying bug in my bedroom. The insect was greyish in colour, and when i tried to kill it, it will flap its wing and release some brown spore/powder. Anyone has any idea if the insect a dangerous one? and the brown thingy released too? P.S. I killed it by wrapping tissue paper...
  43. A

    Consensus: Streak in Image an Insect

    Hey everyone, APOD just announced today that the consensus regarding the strange streak in the Australian picture that people claimed was a meteorite is likely just an insect after all. Here's a more detailed explanation- http://www.cloudbait.com/science/darwin.html
  44. wasteofo2

    How do insect stings/bites harm you?

    Why is it that when you get stung by a bee or bitten by a mosquito that the area around it becomes inflamed? I remember hearing something on the discovery channel that snake venom was just harmful enzymes which digested your flesh, is that how all venom works?
  45. L

    Could an Insect in the Toilet Be the Answer to My Brother's IBS?

    My first post! Okay...this is going to sound really weird. My 32 year-old brother is CONVINCED there was an insect inside of him (not to be too graphic..but he found it in the toilet, after using). He said it resembled a silverfish or earwig and was alive. I say this is impossible...it had...
  46. K

    Do All Insects Come From Eggs? Answers Revealed

    Do all insects come from eggs? Are any the result of chemical reactions alone?
  47. himanshu121

    Unveiling the Mystery of Blood & Insect Colors

    What determines the Colour of BLOOD And why the colour of insects different? I don't know Biology But i want the answer for above just to add to my knowledge
  48. Ivan Seeking

    Robot insect walks on water

    "Scientists have developed a robotic insect which walks on water. The team, based at the Massachusetts Institute of Technology (MIT) in the US, were testing out a theory about how one family of foraging insects performs the same trick" http://news.bbc.co.uk/2/hi/science/nature/3126299.stm