Introduction / Context:
The housefly is a common household insect and an important topic in basic hygiene and public health. Understanding its life cycle helps explain why uncovered food spoils quickly and how diseases can spread. One key stage in the life cycle is the time taken for the eggs to hatch into larvae (maggots). Exam questions often ask for an approximate number of hours to emphasize how rapidly housefly populations can increase under favourable conditions.
Given Data / Assumptions:
• The question asks for the approximate time in hours required for a housefly's egg to hatch.
• We are looking for a realistic biological range, not an exact single minute value.
• The options provide different hour ranges around one to three days.
Concept / Approach:
Under warm and suitable conditions, housefly eggs hatch quite quickly. Scientific observations show that eggs typically hatch within roughly 8–20 hours, often summarised in textbooks as ‘‘about one day’’ or ‘‘within 24 hours’’. This short incubation period explains why neglected garbage or uncovered food can soon be filled with maggots. Therefore, the best option is the one that captures this rapid hatching time close to one day, rather than much longer periods like 36, 48 or 72 hours.
Step-by-Step Solution:
1. Recall the housefly life cycle: egg → larva (maggot) → pupa → adult.
2. The eggs are laid in moist, organic material such as garbage, manure or rotting food.
3. In normal warm conditions, these eggs hatch very quickly.
4. Reference values show hatching generally occurs within about 8–20 hours, which is often rounded to approximately one day.
5. Options of 36, 48 or 72 hours are significantly longer than the typical hatching time for housefly eggs.
6. Hence, the most accurate option is ‘‘Within about 8–20 hours (approximately one day)’’, which matches biological observations.
Verification / Alternative check:
Public health and entomology references frequently state that housefly eggs hatch in less than one day under favourable conditions. Even if minor variations occur due to temperature or humidity, the commonly accepted exam value is that hatching takes roughly one day or less. Therefore, any option suggesting two or three days would be inconsistent with standard biological data.
Why Other Options Are Wrong:
Option B, ‘‘About 36 hours’’, extends beyond the usual upper range and underestimates how quickly infestations can start. Option C, ‘‘About 48 hours’’, and option D, ‘‘About 72 hours’’, are even more unrealistic for the normal development of housefly eggs and do not align with typical life cycle descriptions. In exam practice, such larger values are used as distractors to test whether the student remembers the short incubation time.
Common Pitfalls:
A common mistake is to assume that all insect eggs take several days to hatch, leading students to choose 48 or 72 hours. Another pitfall is ignoring the phrase ‘‘about’’ or ‘‘approximately’’ and expecting a single exact number. In biology, time spans often vary slightly, so it is safer to remember that housefly eggs usually hatch within roughly one day, typically in the 8–20 hour range.
Final Answer:
Housefly eggs generally hatch into larvae
within about 8–20 hours (approximately one day).
Discussion & Comments