Lesson 2 ·Class 9 · Hygiene — [A Key to Healthy Life] · Flow Lab
The Housefly as a Carrier
How a fly moves disease from filth to food.
A housefly does not bite and injects nothing. Follow how it spreads disease anyway.
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🗑️ Step 1 of 8 · It breeds in filth
Eggs are laid on garbage, dung and exposed refuse, where the maggots develop.
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The housefly is a MECHANICAL carrier — it merely transports germs on its body. It is not a host, and the germ does not develop inside it.
What this lesson covers
What you do
- Compare this with the mosquito, which IS a host and in which the parasite develops. That difference matters.
Challenges to clear
- Advance to the step most people do not know about.
- Reach the step that stops the whole chain.
- Follow the whole route through.
The task
A housefly does not bite and injects nothing. Follow how it spreads disease anyway.
What this lesson covers
- It breeds in filth — Eggs are laid on garbage, dung and exposed refuse, where the maggots develop.
- It feeds on waste — The adult settles on faeces and rotting matter, picking up bacteria on its hairy legs and body.
- It carries germs on its body — Millions of bacteria cling to the hairs of its legs and to its sticky foot pads.
- It lands on uncovered food — Every germ on its body is now on your food.
- It liquefies the food to eat it — A fly cannot chew. It spits saliva and regurgitated gut contents onto the food to dissolve it — germs and all — then sucks it up.
- It defecates while feeding — Flies pass faeces constantly as they eat, leaving further contamination behind.
- You eat the food — Cholera, typhoid, dysentery, diarrhoea and food poisoning all travel this route.
- Breaking the chain — Cover food, dispose of refuse properly, and keep drains and dustbins closed. Remove the breeding ground and the fly cannot multiply.
Hint
The housefly is a MECHANICAL carrier — it merely transports germs on its body. It is not a host, and the germ does not develop inside it.