Leg structure
The legs of insects are divided into segments - segments that are movably connected to each other. Each leg articulates with the body at the coxa, located on the lower surface of the body. From the coxal cavity, in order, there is the coxa, then the trochanter, femur, tibia and tarsus. The first two segments are “responsible” for the mobility of the leg relative to the body, the rest are for the movement of the insect along the surface. The junction of the thigh and lower leg - as in the body of higher animals - is called the knee, or knee joint. [3]
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Structure of insect legs
1 - Basin; 2 - Trochanter; 3 - Thigh; 4 - Shin; 5 - Foot
In most cases, each leg segment consists of one part, but sometimes the trochanter is divided into two segments. The shin may have spines and spurs, and, for example, ground beetles have a special narrow notch on it, with which they clean their antennae. [1]
The leg segments usually decrease in thickness from the base to the end, and the tarsus has a slight expansion due to the claws with which the insect clings to the base when moving along relief soil, tree bark, etc. In addition to claws, a suction cup helps insects stay on “difficult” surfaces.
The longest segment of the leg is usually the femur, followed, in descending order, by the tibia, then the tarsus, coxa and trochanter. This size ratio is most common, but it is not an absolute rule. There are many species whose limbs look completely different. [3]
All insects lead different lifestyles. Some must be able to climb smooth stems, some must swim in water, while others are predators and must have the appropriate “devices” for hunting. Depending on this, the structure of the legs can vary greatly. They are divided into specializations, or types.
Caterpillar legs
Thoracic and abdominal legs of the hawkmoth caterpillar: 1 - thoracic legs, 2 - abdominal legs.
Termites
Life cycle of termites. 1 - eggs. 2 - larva. 3 - accessory sexual individuals. 4 - working termite. 5 - soldier. 6 - reproductive larva. 7 - winged sexual individuals. 8 - wingless sexual individuals. 9 - male. 10 - female.
Termites are an order of herbivorous insects. At first glance they resemble ants, but they are not even related. Termites are relatives of cockroaches and belong to insects with incomplete metamorphosis.
Termite home
Termite mound in Kakadu National Park (Australia)
Termite nests vary enormously in appearance, size and the materials from which they are constructed. The size of the nests sometimes reaches several meters. Inside the termite mound there are numerous and varied rooms, halls, and empty galleries. There are warehouses with supplies, children's rooms, rooms for workers, etc.
Types of legs in larvae
The legs of larvae (caterpillars) are very different from the legs of adults. They lack division into segments and other anatomical features. The larvae have short, usually soft, numerous legs that end in a wide or narrow sucker. There are thoracic and abdominal legs, as, for example, in the hawkmoth caterpillar (photo) . [2]
Running legs
N – running legs
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Types of legs in adult insects
Runners
Such limbs can be found in those who are forced to quickly move after live prey. For example, the fragrant beauty (photo) has long, thin legs that allow it to be more agile. [4]
Digging legs
N – digging legs
Digging
They are found in insects that live in burrows or are pests of the root system of plants. A well-known example is the Common Mole cricket (photo) , the first pair of legs of which are transformed into short, thickened limbs, equipped with powerful muscles and ending in a rounded, flattened tarsus with jagged edges. Thanks to this, she manages to break up dense lumps of soil and dig passages in it. [4]
Swimming legs
N – swimming legs
Swimming
This type of legs is a relative rarity, because such modified limbs in the form of “oars” are necessary only for those few insects that live in water. For example, if you look at a water bug (photo) , you can see that they are distinguished by a flattened, streamlined shape without notches or thickenings. This helps to move much faster in water, but if the beetle accidentally lands on land (which is possible, at least, because all insects breathe atmospheric air), such limbs will even interfere with movement. [1]
Jumping legs
H – jumping legs
Jumping
The four-segmented hind legs of the large green grasshopper (photo) and other representatives of the Grasshoppers are distinguished by the large length of the thighs and tibias, as well as their special connection (“back knee”), which allows them to move distances tens of times greater than the size of their body. [1]
Grasping legs
N – grasping legs
Grasping
The front pair of grasping legs can be seen in a praying mantis (photo) , which, with their help, “sorts out relationships” with relatives or hunts small and medium-sized insects, not only pests, but also beneficial ones, for example, bees. [4]
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walking legs
N – walking legs
Walking
In structure, they are not particularly different from running segments, but usually have a shorter length and a smaller difference in size between adjacent segments. Walking legs are found in many Beetles, for example, weevils or leaf beetles (photo) . [4]
Collective legs
N – collective legs
Collective
On the lower leg and tarsus of the hind legs of a honey bee (photo) , there is a special device - a basket for collecting pollen. [4]
Ants
Forest dwelling of ants
Ants are the closest relatives of wasps and bees. An anthill, dotted with a complex system of passages, is a miracle of insect construction technology. Up to 1.5 million ants can live in such a dwelling. They maintain constant temperature and humidity there, for which they raise needles and twigs up.
Everyone has their own role
Anthill structure
In an anthill there is a strict hierarchy and distribution of roles. It is controlled by the queen, a female who lays eggs. Worker ants are also females, but they do not produce offspring as long as the queen is alive. Its lifespan is 15-20 years, that of a worker ant is up to 7 years, and that of males is only one season. Moreover, males do not participate in the life of the anthill and die immediately after mating. In the immediate vicinity of the queen there is a retinue consisting of 10-12 worker ants, who take care of her: lick and feed her.
Ant farm
Ants graze aphids on plants growing nearby and protect them. On demand, the aphid secretes excess nectar. To “milk” the aphid, the ant tickles its abdomen with its antennae.
It turns out that not only people, but also ants are involved in animal husbandry. Although they are active predators, they also keep “livestock”. Its role is played by aphids, and the ants eat not only the aphid itself, but also its secretions. This is not a form of parasitism, since without the ant's care the aphids would have died much earlier from other predators.
According to rough estimates, there are 1 billion billion (1 quintillion) ants in the world, belonging to 12 thousand species. Their total biomass is approximately equal to the biomass of humanity.
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Insects
Insects belong to the largest class of animals, uniting a large number of groups. Their body, like that of all animals, is segmented, with articulated appendages. It is covered with a less or more hard exoskeleton, which contains the polysaccharide chitin.
- relatively small sizes;
- two pairs of wings (some are missing);
- three pairs of legs.
To date, 900,000 species of insects have been described, but there are many more of them - several million, some of them in a single copy. A number of shapes represent beautiful creations, such as butterflies.
Most insect species are terrestrial, but there are also those that lead an amphibious lifestyle. They are found in lakes and rivers, deep caves and deserts. Some species regularly make long flights, others spend their entire lives inside some fruit or even a seed.
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Life cycle
The development cycle takes place in 3-4 phases.
An incomplete cycle is considered when an individual goes through 3 phases: egg-larva-imago. This cycle is characterized by the external similarity of offspring and parents. There is a slight difference in size and structure (bug, grasshopper, aphid).
The complete development cycle consists of 4 stages of insect development: egg-larva-pupa-imago. The adult differs from the larva in its lifestyle and diet. A bright and beautiful representative of the complete phase of transformation is the butterfly.
The larva is mostly a fatty body that accumulates substances for further metamorphosis. After several molts, she freezes, stops eating and drinking, sometimes she can create a cradle for herself, and soon she turns into a pupa.
The pupa is tightly packed in a chitinous shell; it can breathe, but is inactive. Sometimes it moves its abdomen (butterflies), but some types of pupae move very actively in the ground (flies) or in water (mosquitoes).
Imago is an adult insect. After emerging from the cocoon, butterflies must spread their wings to complete their transformation.
Number of legs in insects
So how many legs do insects have? One of the distinguishing characteristics of this class is the presence of three pairs of paws . They are all located in the thoracic region, with one pair on each of the three component segments.
Ancient insects also had legs on their abdomen, which is still reminiscent of the presence of rudimentary appendages in some modern species.
Under the influence of a certain lifestyle during the process of evolution, these creatures developed several types of paws. The most common of them are running and walking. Primitive insects have just such three pairs of legs. For some representatives of the superclass, changes in external conditions and subsequently in the manner of movement entailed modification of the limbs. The middle pair of legs did not undergo specialization during evolution. It is needed for walking.
Habitats
Insects inhabit the entire planet. They live in Antarctica (the bell mosquito) at extremely low temperatures, some individuals can survive at temperatures of +60 in hot springs (the bell mosquito from Nigeria).
Insects climb high into the mountains. A species of Red Apollo butterfly lives in the Everest region at an altitude of about 6000 km above sea level.
Insects have adapted to living conditions and places of residence. They have changed, adapted to environmental conditions and continue to evolve as they develop resistance to the pesticides that humans use to combat them. It is believed that even after a nuclear attack, some insects (cockroaches) will survive.
How are limbs constructed?
The fact that insects belong to the class arthropods is confirmed by the structural features of the legs. They consist of several segments. The main segment is the coxa, which is attached to the corresponding segment of the chest and has a certain shape. Different types of insects have different shapes. In some, this segment looks like a transverse cylinder or ball, in others, the coxa looks like a wide leaf or cone. The mobility of the limb directly depends on the shape of the coxa.
The smallest segment, motionlessly articulated with the thigh, is called the trochanter. In some bugs it is double.
The thigh is connected to the lower leg by the knee, the leg ends with a paw with small claws. The paw consists of several (2-5) flaxes that are connected to each other.
Scientists, studying the number of limbs in insects of various classes, unexpectedly came across the fact that some of their representatives have an interesting mechanism in their structure - a gear. It can be represented schematically in the form of two interlocking wheels with notches. These wheels, through protrusions, interact and synchronize movement. This mechanism allows insects to jump at tremendous speed.
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How to make your garden more attractive to entomophages?
Of course, you can simply buy these necessary helper insects at the Institute of Plant Protection, but if they don’t like it in your garden, they will simply leave it. What will make your site a “paradise” for such “insects”?
- Attractive plants. Plant crops that you and entomophages need, such as flowering mustard, parsley, and creeping thyme. Celery, cumin, and coriander are also suitable.
- Plant the necessary plants in such a way that they bloom throughout the entire summer season and attract beneficial insects with their aromas, even from a remote distance.
- Sow bluegrass, alfalfa and meadow fescue in the spring. If these herbs are not removed after mowing, then all your entomophages will find an excellent refuge in such a “litter.”
- Also, the preservation and breeding of entomophagous insects is greatly facilitated by: irrigation (in dry places), and regular mulching of the soil between the rows in the beds and sodding in the orchard.
- It is especially important to take into account the vital functions of entomophages located on your land, and to carry out various protective treatments of plants taking them into account. This approach will allow you to keep your assistants alive and capable as much as possible.
If you are not sure which insects are human helpers, do not crush bugs again, because the likelihood that this is a beneficial insect is high. We know almost all pests by sight. And although not all entomophagous insects are well studied, they constantly perform their service and help us curb outbreaks of insect pests.
Limb types
The most ancient are walking and running legs in insects. All other limbs took a long time to develop. It was a natural process associated with the need to adapt to the environment.
- Runners . They have an elongated shape and are slender. Consist of narrow or wide legs, lower leg, thigh and coxa. Examples of such legs are the legs of ground beetles and cockroaches;
- Walking legs . Designed for slow movement. Leaf beetles, longhorn beetles, and beetles that slowly crawl from leaf to leaf have such paws;
- Representatives of the order Orthoptera (grasshopper, locust, cricket) have jumping limbs Their last pair of legs is powerful and long. Many orthopterans jump eighty centimeters high; if they straighten their wings, they can cover up to 10 meters in one jump;
- The swimming legs (usually the hind legs, less often the middle ones) are covered with long hairs that form a wide rowing surface of a kind - an oar. Representatives with such limbs mainly live in bodies of water. They swim and dive well. These are, for example: swimming beetles, water lovers, smooth bugs;
- Digging - most often the first pair of legs. These limbs are powerful, short and flat.
- Collective limbs or basket limbs . Bees and bumblebees have it. The hind legs have special areas surrounded by chitinous, long hairs - baskets. Moving from flower to flower, the bees get dirty with pollen that sticks to the hairs. Using special brushes on its legs, the insect collects pollen in a basket, takes it to the hive and deposits it in the honeycomb.
- Suction limbs . In the males of some species (ground beetles, diving beetles), the legs at the ends of the tarsi have expanded segments. During reproduction, males use this device to clasp females when mating.
- Grasping legs armed with sharp spines. They are used by the predator (mantis) to hold its prey.
Bees
A bee family can number from 50 to 100 thousand individuals. Most of these worker bees are sterile females whose modified ovipositor serves as a stinger. They build honeycombs, clean the hive, collect nectar, care for the queen and larvae, and protect the hive from enemies. Worker bees live for one warm season.
How does the life of a bee colony work?
Bee development stage
In a bee family, the main bee is the queen bee, who lays up to 2000 eggs per day. The queen bee is larger than worker bees and lives for about 5 years. By the beginning of summer, young animals appear in the hive, and the family prepares for division. Excitement and bustle begin among the bees: a new queen is about to emerge from the pupa. Before this happens, the old queen, along with some of the worker bees, leaves the hive: the bees swarm. For some time, the swarm of bees that has flown out swirls in the air and then hangs in a huge ball somewhere on a tree.
How a bee produces honey
Honey is a valuable product used as a remedy for many diseases.
Bees have a difficult stomach. Associated with it is the honey comb, where honey is formed from nectar collected on flowers. The bee regurgitates part of the nectar or honey from the crop into the cells of the honeycomb or transfers it to other bees. And the rest of the nectar enters the true stomach through a special valve - the gastric mouth. This is how the bee feeds and builds honeycombs, which it seals with wax—it also produces it itself.
Meaning of the Honey Bee
Special frames with wax plates are inserted into the hives, in which the bees build their honeycombs and deposit honey.
Many centuries ago, people learned to keep honey bees and use beneficial bee products - honey and other components - to make medicines. Recently, the role of bees as the main pollinators of agricultural plants has become increasingly important. The benefits they bring from this many times exceed all other income from beekeeping.
The honeycomb cells are regular hexagons. The bottom of the cell is made up of three rhombuses, forming a prism. Each diamond simultaneously serves as a part of the neighboring honeycomb. The cells intended for breeding differ in shape from those in which honey is stored.
Insect limbs
Why do insects need legs? There seemed to be only one definite answer to this question: for movement, of course. In fact, the legs of insects perform several functions.
The function of an insect's limbs depends on the environment in which it lives, how it feeds and defends itself. Therefore, the paws of different species are adapted for digging passages, burying dead animals, making nests, protecting against attack, capturing food, jumping, swimming, and running.
Lifestyle and protection
Insects are forced to adapt and protect themselves. They use active deterrence, mimicry and cryptism. Bees, wasps, and scorpions actively defend themselves with their stings. The Peacock Eye butterfly scares everyone with spots on its wings. Ladybugs are repelled by coloring.
Mimic animals look like dangerous insects, but are actually harmless (glassworts look like wasps), or blend in with the surrounding nature (mantises are green in color, hiding them among the foliage).
Cryptism is the ability to merge with the environment (some types of caterpillars, grasshoppers).
Insects are also diverse in their lifestyle: they can live in a social group (ants, termites), or they can live alone (many butterflies, beetles).
It is interesting that insects in a social group differ both in appearance and in the work they perform (workers, guards, queen).
How are the limbs of insects arranged?
The class insects belongs to the phylum arthropods. This name confirms the structural features of the legs of insects: they consist of several segments.
The main segment attached to the corresponding segment of the chest is called the coxa. The basin has a strictly defined shape. It differs among different types of insects. In some representatives the coxa looks like a ball or transverse cylinder, in others it looks like a cone or a wide leaf. The mobility of the limb depends on the shape of the coxa. The smallest segment is called the trochanter. Sometimes it is double. The trochanter is motionlessly articulated with the femur.
The longest component of the limb is the femur. It is longer than all parts of the leg and looks like a long cylindrical stick.
The next section is called the lower leg. It is comparable in size to the thigh, and together with it makes up the longest part of the insect’s limb.
The thigh and lower leg are connected using the knee. The leg ends with a paw. It consists of several flaxes movably connected to each other, their number is 2 - 5. The foot is armed with small claws. Usually there are two, and extremely rarely one.
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Even insects that fly or swim need legs.
What to do?
In a forward-looking paper that brings together findings from 11 studies, scientists outline key ways world leaders could help reduce insect populations. These efforts should include closer monitoring of the health and abundance of insect populations, as well as stressors ranging from rising temperatures to pesticide use. In addition to creating new monitoring, the authors call for more resources to be used to analyze existing data, many of which receive little or no analysis.
Types of Insect Limbs
The most ancient are the running and walking legs of insects. The remaining types of limbs appeared in the process of long-term development, and, as a rule, are associated with various adaptations to environmental conditions.
The running legs have an elongated shape. They are slender, and the tarsus, lower leg, thigh and coxa are narrow or wide. This type of limbs is present in cockroaches and ground beetles.
Walking legs are designed for slow movement. These are the legs of beetles - longhorned beetles, leaf beetles, crawling from leaf to leaf, leisurely gnawing leaves.
Insects need limbs to move around.
- Swimming limbs
The hind legs of insects usually become swimming, and less often the middle legs. They are covered with long hairs that form a wide rowing surface - a kind of oar. Basically, representatives with such limbs live in bodies of water and swim and dive excellently. These are swimming beetles, smooth bugs, and water lovers.
Representatives of the order Orthoptera have jumping legs. These include locusts, grasshoppers, and crickets. Their last pair of legs is very long and powerful. Many representatives of Orthoptera jump in heights of up to eighty centimeters, and if they spread their wings at the same time, the distance covered in one jump reaches about ten meters.
Digging legs are characteristic of the mole cricket, dung beetle, and May beetle. Usually the first pair of legs become digging legs. The limbs of this type are powerful, flat and short.
The legs of grasshoppers give them the ability to move tens of meters in a matter of seconds.
- Collective limbs
The limbs of bees and bumblebees are called collective or basket limbs. On the hind legs of these insects there are special areas surrounded by long chitinous hairs; these are baskets. Bees move from flower to flower and get dirty in the pollen that sticks to the hairs of their bodies. With special brushes located on the legs, the bee collects flower pollen into baskets.
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the adhesive dust particles form a lump called “polnoka”. The bee carries pollen into the hive and deposits it in the honeycomb. Bee bread soaked in nectar is formed; it serves as a reserve protein food for the entire bee family.
Thanks to the collecting type of legs, the bee can “save” pollen.
- Grasping legs
Grasping legs of a praying mantis. They are armed with sharp spines, which the predator uses to hold its prey.
The legs of males of some species of insects - swimming beetles and ground beetles - have expanded segments at the ends of the legs. During the breeding season, males use these devices to grasp females during mating.
Grasping legs help not only to hold prey, but also to the female during mating.
Nutrition
What types of insects are there based on their feeding habits?
- Herbivores (bark beetles, locusts, caterpillars) consume tissues of living plants. They are often pests of garden crops, and in some cases they represent a natural disaster.
- Carnivores (fly larvae, ground beetles, swimming beetles) feed on small insects.
- Saprophages (horned beetles, wood flies) feed on dead animals and plants.
- Coprophagous (dung beetles) - feed on excrement and humus.
- Bloodsuckers are already clear from the name - they suck the blood of warm-blooded animals, including humans (mosquito, horsefly).
- Pollen eaters and nectar suckers are pleasant creatures. They feed on nectar and pollen from flowers (most butterflies include them).
