Despite the widespread and increasing prevalence of bed bug infestations in different regions of the country, there is limited data on involved species and their frequencies in Iran. The available reports indicate the presence of two species of the family Cimicidae in Iran. Cimex lectularius L. had been the dominant species in Iran for many years, and all bed bug infestations in different facilities were attributed to this species. In recent years, reports of the presence of Cimex hemipterus (Fabricius) have increased in the country. This study tried to illuminate the presence, distribution and abundance of these two species in eastern Iran. Samples were collected between March 2021 and May 2023 from the four eastern provinces of the country, including North Khorasan, Khorasan Razavi, South Khorasan and Sistan & Baluchistan. Bed bugs were caught by hand using forceps and transferred to the parasitology laboratory of Ferdowsi University of Mashhad in plastic vials. The collected specimens were identified under a stereomicroscope based on standard morphological keys. Overall, 38 isolates were collected from residential places, including residential houses, apartments and student dormitories. Also, four archived isolates were provided and studied. All the specimens collected during the study period were identified as C. hemipterus. Of the Four archived populations, two populations were found to be C. lectularius, and two populations were C. hemipterus. This study showed that C. lectularius was more abundant in the past in eastern Iran, and this species has been replaced with C. hemipterus in this region.

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