Self-Assessment Questions (SAQs) for Study Session 10

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.

SAQ 10.1 (tests Learning Outcomes 10.1 and 10.2)

The resting habits of mosquitoes are very important for IRS. Which of the following sites can serve as resting places for a blood-fed mosquito, so they should be sprayed with insecticide? Which ones cannot be sprayed?

  • Walls of houses
  • Furniture in houses
  • Streams
  • Animal shelters
  • Lakes
  • Rivers
  • Latrines.


Walls of houses, animal shelters and latrines, as well as household furniture, can serve as resting places for blood-fed mosquitoes, and should be sprayed with insecticides.

Streams, lakes and rivers are not resting places for adult mosquitoes.

SAQ 10.2 (tests Learning Outcome 10.2)

Which of the following statements is false? In each case, explain what is incorrect.

A  Blood-fed mosquitoes rest on either the inside of houses or in vegetation outdoors.

B  Mosquitoes that rest outside houses after feeding are easier to control with IRS.

C  After taking a blood meal, mosquitoes have to rest about 10 days before laying their eggs and seeking their next blood meal.

D  Blood-fed mosquitoes can often rest on the outside walls of houses.

E  IRS kills mosquitoes entering houses and resting on sprayed walls and furniture.


A is true. Blood-fed mosquitoes can rest either indoors or outdoors.

B is false. Mosquitoes that rest outside houses are harder to control using IRS.

C is false. After taking a blood meal mosquitoes rest for about two days (not 10 days) before laying eggs.

D is false. Blood-fed mosquitoes do not usually rest on the outside walls of houses. They prefer shaded and undisturbed sites.

E is true. IRS only kills mosquitoes entering and/or resting in sprayed houses.

SAQ 10.3 (tests Learning Outcome 10.3)

You will be responsible for undertaking IRS in your village and before you start the operation you have to make sure you have all the resources ready. What are the items you have to request from the District Health Office, and what do you have to do at the community level?


You have to request the following items from the District Health Office:

  • Spray pumps, insecticides, spray pump spare kits, tool kits for pump maintenance, personal protective equipment.
  • At the community level you have to select and train spray operators.

SAQ 10.4 (tests Learning Outcome 10.3)

What is the capacity of the spray pump used for IRS in Ethiopia? What is the surface area that can be sprayed by one full spray pump of insecticide?


  • The spray pumps used in Ethiopia have eight litres capacity.
  • One spray pump full of insecticide can spray 200 m2 of surface area.

SAQ 10.5 (tests Learning Outcomes 10.3 and 10.5)

Your village has 800 households and the average housing unit per household is 1.5. At the end of your spray operation, your record shows that 900 housing units were sprayed and the rest were unsprayed.

  • a.How many housing units were expected to be sprayed?
  • b.How many housing units were unsprayed?
  • c.What is the coverage of this IRS operation? Express you answer as % of housing units sprayed.
  • d.Is the coverage of this IRS operation acceptable? Say why or why not.


  • a.800 households multiplied by 1.5 housing units per household = 1,200 housing units.
  • b.900 housing units were sprayed. Therefore 1,200 – 900 = 300 housing units were unsprayed.
  • c.The coverage of this IRS operation is (900/1,200) x 100 = 75%.
  • d.The coverage is not acceptable; the minimum coverage acceptable for IRS to be effective is 85%.

Read Case Study 10.1 carefully and then answer the questions below it.

Case Study 10.1  A village IRS programme

Your village has 500 households and each household has two housing units. One spray operator sprays 20 housing units per day. You have five spray operators with five spray pumps to undertake the operation. The average surface area of one housing unit is 100 m2. From Section 10.5 you have learned that one spray pump of insecticide (one sachet) covers 200 m2 surface area.

SAQ 10.6 (tests Learning Outcomes 10.3 and 10.5)

  • a.How many working days will be needed to spray the entire village?
  • b.How many sachets of insecticide do you need for the village?
  • c.How many sachets does one spray operator need to carry for one day’s work?

In each case, explain how you arrived at your answer.


  • a.Ten days. This is worked out as follows: there are 500 x 2 = 1,000 housing units. Number of units 5 spray operators can spray in one day = 5 (spray operators) x 20 (units each operator sprays in a day) = 100 units. So the number of days to spray the entire village of 1,000 units at 100 units per day = 10 days.
  • b.Five hundred sachets. This is worked out as follows: one sachet sprays 200 m2 which is equal to 2 housing units. 1,000 housing units divided by 2 units per sachet = 500 sachets.
  • c.Ten sachets. This is worked out as follows: one spray operator sprays 20 housing units per day. One sachet is needed to spray 200 m2 surface area, which is enough for 2 housing units of 100 m2 each. To spray 20 housing units at 2 housing units per sachet = 10 sachets.

SAQ 10.7 (tests Learning Outcome 10.6)

Which of the following statements about the safe handling of insecticides is false? In each case, explain what is incorrect.

A  Spray operators need to wear a shirt and trousers during spraying.

B  Hands and faces should be washed with soap after spraying, and before eating or drinking.

C  Any leftover insecticide should be poured into rivers.

D  Spray operators can keep wearing contaminated clothes for a week without washing.


A is false. Shirts and trousers do not give enough protection. Spray operators also need to wear a hat, mask, goggles and gloves etc. to protect themselves from contamination.

B is true. Hands and faces should be washed with soap after spraying and before eating or drinking

C is false. Any leftover insecticides should be disposed of in a pit prepared for this purpose; they should never be poured into a river (or other water body).

D is false. Contaminated clothes have to be changed and washed immediately.

Summary of Study Session 10