How to protect my plants from these insects

[Izhar]

Would common branded household insecticide that's used against cockroaches etc be effective against mealybug?

Not at all, use the pesticides which are intended for plants only... the spray must be applied for continuous three days then on weekly basis (depending on the severity of attack)

This is a common mistake that gardeners make i.e. they spray once, thinking that the pests will be eliminated. A regular spray is must, not only on plants but on the pots and other stuff near them as many pests lay egg in cracks of pots, walls and ground...

[mahira]

try spraying acetamiprid. people here suggested me that n it totally worked for me.. i hate mealy bugs if i spot them in any plant i spray alot n get rid of it n yup regular spraying is necessary

[FSKamal]

I often see them on the stems of my tomato plants, I pull them with my hands and clear them off, later wash the stems. they never appear again.