Question

Common house fly (Musca nebulo) lays eggs on
(a)Cow/ Horse dung
(b)Stagnant water
(c)Hanging ropes
(d)Open meats and sweets

Answer 1

Hint: Musca nebulo is the common Indian house fly. The color of the body is gray. The body is divided into head, thorax, and abdomen. The female fly mates only once and stores the sperm for later use. They lay batches of about 100 eggs. These soon hatch into legless white larvae, known as maggots. After two to five days these metamorphosed into reddish-brown pupae, about 8 millimeters. Adult flies normally live for two to four weeks and may lay hundreds of eggs over that time. They are holometabolous insects, their life cycle includes four stages; egg, larva, pupa, and adult.

Complete answer:
The house fly feeds on any organic fluid, it’s mouthparts are modified for lapping up liquid food. House flies also feed on solid substances, especially sugar and sweets. The copulation of fly takes place on earth, not in the air. The copulation takes a few minutes. Four days after mating, the female house fly lays her eggs in stable manure by preference but failing to find this, it may lay in human feces, garbage, or decomposing animal and vegetable matter. The conditions required for laying eggs are moisture and a favorable temperature, hence stable manure or human feces should not be dry. So they usually prefer decaying organic matter such as food waste, grass clippings, carrion, or feces, which will provide suitable food for the developing larvae. The egg hatches in 8 to 24 hours depending upon the temperature and the larvae emerge in dung. Their larvae are called maggots. When the larva is ready to pupate, it searches out a dry, dark service of the manure, the body contracts and segments are modified to form a pupa.

Additional Information: -Egg of house fly is whitish, cylindrical, and 1mm long. It has two ribs like thickening on one side.
-Larva are highly modified without a distinct head, thorax, or abdominal limbs. They are covered by soft chitin, such a larva is known as an apodous larva.
-The larva when it hatches from the egg is the first instar larva. The first instar lasts for 2 to 3 days, then it mounts and becomes the second instar larva.
-The second instar larva lasts for a day, then it mounts to form the third instar. It has a small insignificant head, followed by 12 segments.
- The third instar lasts for 3 to 5 days. The total larval period is from 6 to 8 days. During this period larva mounts twice, feeds on decaying organic matter, and grows in size. It feeds on substances in which it was hatched.
So, the correct answer is ‘cow/horse dung.’

Note: They serve as vectors of causative agents of typhoid, cholera, diarrhea, dysentery, conjunctivitis, etc. The disease-causing agents are either transmitted by the body hairs or by tarsi which are transmitted to food or surfaces when the fly lands. Housefly follows holometabolous development and life history. It involves a total or complete metamorphosis. In holometabolous development, embryo hatches out as larva. It undergoes complete metamorphosis and transforms to pupa which, in turn, grows in size, develops wings and gonads, and becomes adult. The pupal stage often includes an interval of physiological dormancy called diapause.