Types of pesticides

There are multiple ways of classifying pesticides.
Algicides or algaecides for the control of algae
Avicides for the control of birds
Bactericides for the control of bacteria
Fungicides for the control of fungi and oomycetes
Herbicides for the control of weeds
Insecticides for the control of insects - these can be ovicides (substances that kill eggs), larvicides (substances that kill larvae) or adulticides (substances that kill adults)
Miticides or acaricides for the control of mites
Molluscicides for the control of slugs and snails
Nematicides for the control of nematodes
Rodenticides for the control of rodents
Virucides for the control of viruses (e.g. H5N1)
Pesticides can also be classed as synthetic pesticides or biological pesticides (biopesticides), although the distinction can sometimes blur.
Broad-spectrum pesticides are those that kill an array of species, while narrow-spectrum, or selective pesticides only kill a small group of species.
A systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is usually upward (through the xylem) and outward. Increased efficiency may be a result. Systemic insecticides which poison pollen and nectar in the flowers may kill needed pollinators such as bees.
Most pesticides work by poisoning pests.