Wings and Flight in Insects – Direct & Indirect flight Muscles & More

Wings & Flight in Insects

The ability to fly is one of the elements responsible for the biological and evolutionary success of insects. The wings are flattened areas of the integument, occurring dorsolateral in between the nota and pleura of the meso- and metathoracic sections.

Wings in living insects serve a variety of functions, including active flying, moving, parachuting, elevation stability while leaping, thermoregulation, and sound production. These are extremely useful in identification. The wings are more or less triangular in form and certain areas might be recognized.

Cross-section through the wing

The membrane is two layers of the integument. Veins consist of nerves, blood areas, and tracheae. Wings do not include muscle.


Irregular network of veins found in primitive insects. Longitudinal veins with restricted cross-veins are common in numerous pterygote groups. Extreme decrease of all veins typical in small insects. Longitudinal veins concentrated and thickened towards the anterior margin of the wing. This offers increased performance and support.


The dark area on the forewing in Hymenoptera, Psocoptera, Megaloptera, and Mecoptera and on both wings in Odonata. Functions as an inertial mass in flight. Reduces wing flutter throughout sliding in odonates, thus increasing flight effectiveness. Offers passive control of the angle of attack in small insects, which improves effectiveness during flapping flight.


Wing folding

Flexion lines lower passive deformation and boost the wing as an aerofoil. Fold lines are utilized in the folding of wings over back.

Flight in Insects

The capability for flight in bugs is believed to have developed some 300 million years ago, and at first, consisted of simple extensions of the cuticle from the thorax. The success of insects throughout the evolution of flight was because of their small size.

Naturally, not all insects have developed wings, including such groups as spring-tails and silverfish. Some parasitic groups are thought to have actually lost their wings through evolution. When wings are present in insects, they frequently include two sets. These consist of grasshoppers, bees, wasps, dragonflies, real bugs, butterflies, moths, and others. Some bugs with big wings, such as Dobsonflies and Antlions, are reasonably poor fliers, while bees and wasps with smaller wings are good fliers.


True flies are a large group of insects with only one set of wings, although they have small stabilizing organs called halteres where a second pair of wings may develop. The halteres vibrate with the wings and sense changes of direction. Flight is one of the main reasons that insects have succeeded in nature. Flight assists insects in the following ways:

  • Escaping from threat
  • Discovering food
  • Finding mates
  • Exploring for new locations to live
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Insect Wing Movement

In a lot of insects, the forewings and hindwings operate in tandem. Throughout the flight, the front and rear wings remain locked together, and both go up and down at the same time. In some insect orders, most especially the Odonata, the wings move separately during flight. As the forewing raises, the hindwing lowers.

Insect flight requires more than a basic upward and downward movement of the wings. The wings likewise move on and back, and turn so the leading or tracking edge of the wing is pitched up or down. These complex movements assist the insect to attain lift, lower drag, and perform acrobatic maneuvers.

Flight muscles

Insects have one of two various arrangements of muscles used to flap their wings:

Direct flight muscles

Direct flight muscles are found in insects such as dragonflies and cockroaches. The wings pivot up and down around a single pivot point. The wings are raised by a contraction of muscles connected to the base of the wing inside (toward the middle of the insect) the pivot point. The wings are then brought down by a contraction of muscles that attach to the wing beyond the pivot point.


Indirect flight muscles

Indirect flight muscles are found in more advanced insects such as true flies. Indirect flight muscles are linked to the upper (tergum) and lower (chest bone) surface areas of the insect thorax. The second set of muscles connects to the front and back of the thorax. The wings are raised by the muscles attached to the upper and lower surface of the thorax contracting.

This brings the top surface of the thorax down and, along with it, the base of the wings. As a result, the wingtips pivot upwards. The wings are then lowered by a contraction of the muscles connected to the front and back of the thorax. This forces the upper surface of the thorax to rise and the wings pivot downwards.


Synchronous and asynchronous muscle
  • Insects that beat their wings less than one hundred times a second use synchronous muscle. Synchronous muscle is a type of muscle that contracts once for every single nerve impulse.
  • Insects that beat their wings more rapidly utilize asynchronous muscle. This is a kind of muscle that contracts more than once per nerve impulse. This is attained by the muscle being stimulated to contract once again by a release of tension in the muscle. This can occur more quickly than through basic nerve stimulation alone.

FAQs (Frequently Asked Questions)

1. What are the primary functions of wings in insects?

  • Answer: Insects’ wings serve various functions, including active flying, movement, parachuting, elevation stability, thermoregulation, and sound production.

2. How are insect wings structured?

  • Answer: Insect wings have two layers of integument forming a membrane with veins containing nerves, blood areas, and tracheae. They lack muscles.

3. What is the significance of Pterostigma in insect wings?

  • Answer: Pterostigma, a dark area on wings, acts as an inertial mass, reducing wing flutter and improving flight efficiency.
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4. How do insects fold their wings?

  • Answer: Flexion lines reduce passive deformation and enhance wing performance as an aerofoil. Fold lines are used in wing folding over the back.

5. When did the ability for flight in insects evolve?

  • Answer: The ability for flight in insects is believed to have evolved approximately 300 million years ago, contributing significantly to their evolutionary success.

6. Do all insects have wings?

  • Answer: No, not all insects have wings. Some groups, like spring-tails and silverfish, lack wings, and certain parasitic groups may have lost their wings through evolution.

7. How do the forewings and hindwings operate during flight in most insects?

  • Answer: In most insects, the forewings and hindwings operate in tandem, moving up and down together. However, in Odonata, the wings may move independently.

8. What is the role of flight in insects?

  • Answer: Flight in insects is essential for escaping danger, finding food, locating mates, exploring new habitats, and overall survival in nature.

9. What are the two types of flight muscles in insects?

  • Answer: Insects have direct flight muscles (e.g., dragonflies) and indirect flight muscles (e.g., true flies) used to flap their wings.

10. How do indirect flight muscles operate in insects?

  • Answer: Indirect flight muscles are connected to the upper and lower surfaces of the thorax. Contraction of these muscles raises and lowers the wings, providing the necessary movements for flight.

11. What is the difference between synchronous and asynchronous muscles in insect flight?

  • Answer: Insects with slower wing beats use synchronous muscles, contracting once per nerve impulse. Insects with faster wing beats use asynchronous muscles, contracting more than once per nerve impulse.

12. How does the evolution of flight contribute to the success of insects?

  • Answer: Flight in insects has been crucial to their success, aiding in escaping threats, finding resources, reproducing, and adapting to new environments.


Wrap up

The tutorial on “Wings and Flight in Insects” provides a comprehensive exploration of the intricate aspects of insect flight. Highlighting the crucial role of flight in the biological and evolutionary success of insects, the tutorial covers various elements, including wing structure, venation, pterostigma, wing folding, and flight mechanics.

  • Insect Flight Importance: Insects’ wings serve multiple functions, such as active flying, movement, parachuting, stability, thermoregulation, and sound production. The tutorial explains the cross-section through the wing, emphasizing the two layers of the integument, veins, and the absence of muscles in wings.
  • Structural Elements: The significance of venation in primitive insects and the role of pterostigma as an inertial mass in flight are detailed. The section on wing folding discusses flexion lines and their role in enhancing wing performance.
  • Evolution of Flight: Exploring the evolution of flight in insects over 300 million years, the tutorial notes that not all insects have wings, with some groups losing them through evolution. The diverse types of wings in various insect orders, including grasshoppers, bees, wasps, dragonflies, and others, are highlighted.
  • Role of Flight: The role of flight in assisting insects in escaping threats, finding food, locating mates, and exploring new habitats is emphasized. Insect wing movement, especially in tandem forewings and hindwings, is explained, with a special mention of the independent wing movement in Odonata.
  • Flight Muscles: The tutorial delves into the intricacies of flight muscles, distinguishing between direct flight muscles (found in dragonflies and cockroaches) and indirect flight muscles (found in true flies). The explanation includes the mechanics of wing movement through contraction and relaxation of muscles.
  • Muscle Complexity: Synchronous and asynchronous muscles are discussed in relation to wing beats per second, providing insight into the complexity of insect flight. The tutorial concludes by highlighting the fundamental role of flight in the success of insects in nature.
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