66

N. Chari et al.

Fig. 5.13 Housefly and mosquito

Diptera

In houseflies and mosquitoes, forewings are the only functional pair of wings used in

flight. These are thin and more or less transparent membranous wings. Hindwings are

modified into small knobbed vibrating organs called halters, which help the insect to

sense its orientation and movement, as well as act as balancing organs and provide

the needed stability during flight (Fig. 5.13). Halters vibrate out of phase with the

wings. Perturbations due to rotations are picked up by tiny hairs near the halters to

give a simple effect of a gyro. Many dipteran fliers have a high wingbeat frequency.

Some mosquitoes flap their wings 1000 times per second. Flies are among the fast

fliers with high wingbeat frequency, increasing with mutilation.

Examples: Houseflies, Mosquitoes and Syrphid Flies.

Neuroptera

It consists of two pairs of wings. Normally, two pairs of wings similar in size, shape

and venation are variable. Many longitudinal and cross-veins are present (Fig. 5.14).

Venation has a network of veins. They are poor and erratic fliers.

Examples: Nerve Winged Insects or Lacewings.

Fig. 5.14 Lacewings