Dragonflies are useful to get rid of aphids and mosquitoes. Bacillus thuringiensis is an example of microbial biocontrol agents that can be introduced in order to control butterfly caterpillars and lepidopteran plant pests. Many members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Baculoviruses are pathogens that attack insects and other arthropods. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications.