Ladybird is useful to get rid of ___________.
Aphids
The correct option is A.
Explanation of the correct option:
Explanation of the incorrect options:
Option B:
To get rid of the larva of mosquitoes, a fish called Gambusia is introduced into the ponds.
Option C:
Boll worms are pests that harm the cotton plants. They can be killed by using baculoviruses.
Option D:
Jassids are also called leafhoppers which can be killed by applying pesticides and insecticides.
Final answer: Ladybirds are useful to get rid of aphids.