Northern Baikal region in the paper includes Kazachinsko-Lensky and Kachug areas of the Irkutsk region and Severobaykalsk and Barguzin areas of the Republic of Buryatia. Information of study of biodiversity, ecology and economic importance of true bugs is given in the article. A brief overview of the history of the study of aquatic and terrestrial members of the Heteroptera order of Irkutsk Region and Buryatia, especially their northern territories is given in this paper. The article deals with Heteroptera’s types of food, the degree of harm or benefit to economic importance. Latitude of food specialization and trophic relations of phytophagous true-bugs with host plants examined. Species polyphages and oligophagous that harm cereals, legumes, crucifers, etc. cultures, and berry bushes and trees were studied. Predatory bugs, especially the representatives of the aquatic fauna, feed on small insects and mites, therefore, predators Heteroptera are the regulators of the numbers of some pests.