External anatomy of insects pdf

Tagma Plural —Tagmata Tagmosis — the evolutionary process in which body segments group into functional units and tagmata are formed.

What type? Leg Modification. Comstock-Needham system. Costa, subcosta, radius, media, cubitus, anal veins. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks.

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Difficulty Beginner Intermediate Advanced. Explore Documents. Lab 3 Insect Morphology External Anatomy. Uploaded by Veneisia Tomlinson.

Did you find this document useful? Is this content inappropriate? Report this Document. Flag for inappropriate content. Download now. Related titles. Carousel Previous Carousel Next. Moths of the Limberlost by Stratton-Porter, Gene, Chua Yek Hong vs. Intermediate Appellate Court These are called " indirect flight muscles" because they have no direct contact with the wings.

They stretch from the notum to the sternum. When they contract, they pull the notum downward relative to the fulcrum point and force the wing tips up. In the more primitive insect orders e. Odonata and Blattodea , the downstroke is initiated by basalar muscles that attach through ligaments directly to the wing's axillary sclerites.

Contraction of these " direct flight muscles" literally pulls the wings into their "down" position. Most other insects have dorsal-longitudinal muscles attached like bow strings to apodemes at the front and back of each thoracic segment. These are " indirect flight muscles". When they contract, they cause the edges of the notum to flex upward relative to the fulcrum point causing the wings to snap down.

During flight, upstroke and downstroke muscles must contract in alternating sequence. There are two different mechanisms for controlling this muscle action, synchronous neurogenic and asynchronous myogenic :. Insects with synchronous control have neurogenic flight muscles, meaning that each contraction is triggered by a separate nerve impulse.

Central pattern generators in the thoracic ganglia coordinate the rate and timing of these contractions. Since nerve cells have a refractory period that limits how often they can fire, insects with neurogenic flight muscles have relatively slow wing beat frequencies typically beats per second.

Insects with asynchronous control depend almost entirely on indirect flight muscles for upstroke dorsal-ventrals and downstroke dorsal-longitudinals.

These muscles have developed myogenic properties, that is, they contract spontaneously if stretched beyond a certain threshhold. When the nervous system sends a "start" signal, the dorsal-longitudinal and dorsal-ventral muscles begin contracting autonomously, each in response to stretching by the other.

Contractions continue until the muscles receive a "stop" signal from the nervous system. Asynchronous control is not limited by the nerves' refractory period, so wing beat frequency in some of these insects notably flies and bees may be as high as beats per second. Such high frequencies produce greater lift with smaller surface area and also improve maneuverability e.

As an insect's wing moves up and down during flight, it also twists about the vertical axis so that its tip follows an ellipse or a figure eight. This sculling motion maximizes lift on the downstroke and minimizes drag on the upstroke. Turning, hovering, and other acrobatic maneuvers are controlled by small muscles attached to the axillary sclerites.

These muscles adjust the tilt and twist of the wing in response to feedback from the central nervous system and sensory receptors that monitor lift and thrust. These legs are usually flattened or equipped with a fringe of long, stiff hairs to improve their performance and efficiency in the water.

Legless larvae and pupae of mosquitoes, midges, and other flies Diptera manage to swim by twisting, contorting, or undulating their bodies. Dragonfly naiads Odonata have a jet propulsion system: they can propel themselves forward by contracting abdominal muscles and forcing a jet of water out of the rectal chamber that houses their respiratory gills. A few aquatic insects, such as water striders, have a whorl of hydrophobic hairs on the tips of their feet. These hairs prevent the insect's legs from breaking the surface tension of the water and allow them to skate on the surface.