Household insecticides are primarily divided into five major categories based on their chemical structure and mode of action.

Pyrethroids are the most common household insecticides — permethrin, cypermethrin, deltamethrin, etc.

They act on insect sodium channels, causing sustained nerve excitation and paralytic death.

They have low mammalian toxicity (because mammals can metabolize them rapidly), but are highly toxic to fish and bees.

Organophosphates were once widely used in agriculture and pest control (dichlorvos, malathion) but due to their higher neurotoxicity in mammals (inhibiting acetylcholinesterase, leading to acetylcholine accumulation), most countries have restricted or phased out their household use.

Carbamates have a similar mode of action to organophosphates but a shorter duration of action; toxicity is slightly lower than organophosphates but higher than pyrethroids.

Neonicotinoids such as imidacloprid and thiamethoxam act on nicotinic acetylcholine receptors; they are more insect-specific and are commonly used in ant and cockroach gel baits.

Insect Growth Regulators (IGRs), such as methoprene and hexaflumuron, mimic or interfere with insect juvenile hormone or chitin synthesis — they act slowly (taking weeks), but are highly target-specific with very low mammalian toxicity — making them the preferred chemical tool in IPM.

When choosing an insecticide, the most important thing is not the brand — but the active ingredient listed on the label.