B. thuringiensis is a spore forming bacterium, which produces a crystal protein as parasporic inclusion in the vegetative cells containing spore. Several different types of crystal proteins are produced by different strains of the bacterium, each protein having a specific and ordinarily narrow insect host range.

This highlights a very important feature of biopesticides: they are specific to only a well defined range of target species. This is in contrast to the chemical pesticides which usually affect a very wide range of target species. This property must be well appreciated by the user of a biopesticide.
B. thuringiensis cells are produced in fermenters, as are other bacteria and fungi. The commercial preparations usually contain a mixture of spores, crystal proteins and inert carriers. The formulation may be in the form of a water dispersible powder, wettable powder, emulsifiable concentrate, flowable concentrate, granules or dust.

Another bacculovirus, the granulosis virus (GV), is also promising and may be used commercially for Spodoptera litura control in India. Commercial production of these viruses is done in the larvae of the target insects, e.g., NPV in Heliothis larvae.

Large scale production of fungi may use solid state fermentation, e.g., Hirsutella thompsonii, etc., a combination of solid state and submerged fermentations, or submerged fermentation, e.g., Beauveria bassiana, etc.