4

Flight Morphology and Flight Muscles

45

Fig. 4.4 Wing and venation

of a housefly

the wing venation has been shown in Fig. 4.3 and that of a housefly which differs

significantly in Fig. 4.4.

Wing Joints

1.

A majority of insects can flex their thin wings over the back when at rest.

2.

There is a complicated articular structure at the wing base than a mere hinged

joint of the wing with the body.

3.

Each wing is attached to the body by a membranous basal area. The membrane

contains a number of small articular sclerites, collectively called “pteralia”.

4.

Pteralia includes a group of “axillaries” which are specially developed only in

the wing flexing insects.

5.

The axillaries contribute to the flexor mechanism. There are first, second and

third axillary sclerites that support the wing.

6.

There are special sclerotized plates such as humeral plate at the base of the

costal vein, distal plate at the base of the cubic vein and proximal plate at the

base of anal veins, and thus, it supports the venation of the wing (Fig. 4.5).

Wing Muscles

1.

The insect flight muscles are highly oxidative in their metabolism and constitute

10–30% of total body mass.

2.

Insect muscles are strictly aerobic and maintain high levels of energy required

during flight. Fuel is carried by the blood to the muscles and O2 through minute

tracheoles by diffusion. Flight muscles have many mitochondria which act as

miniature powerhouses of the cells.

3.

Many wing muscles are large measuring about 10 mm in length and 2 mm in

width.