Epigenetic in insects is an important origin of biodiversity that can convert environmental stimuli into heritable phenotypic changes and biological variation without mutations and independent changes in the DNA sequence, by variation of gene expression levels. Epigenetic may play important roles in the parameters such as development, longevity, reproduction, gender-specific phenotypic variation, immunity, and evolution of both insect-plant and insect-microbe interactions. To investigate the molecular bases of epigenetic, social insects like ants provide a natural experimental system. In social insects, multiple phenotypes and distinct types of individuals arise from a single genome. The existence of alternative phenotypes encoded by the same genome is known as polyphenism. Caste polyphenism is originated from molecular information that once established can be later maintained through epigenetic inheritance. As well as, Host– parasite interactions are intimate epigenetic relationships. Insect Epigenetic mechanisms are divided in to before transcription and post-transcriptional gene regulation. DNA methylation and histone acetylation/deacetylation are before transcription and small non-coding RNAs known as microRNAs are referred to as post-transcriptional gene regulation. Methylation is common throughout the genome and it is reported as the origin of differential gene expression in social insect castes. In general, insects possess relatively low levels of DNA methylation, compared to mammalian systems. Epigenetic studies in insects are not only progressing but also promising to find a solution for pesticide resistance.