Preliminary Observations of Firefly Occurrence in an Urban Area of Bongaigaon, Assam, India

Abstract

Fireflies (Family: Lampyridae) are ecologically important nocturnal beetles whose occurrence can be influenced by habitat conditions, artificial light and other environmental factors. However, baseline information on firefly occurrence remains limited in several urban areas of Northeast India. The present study aimed to document the short-term occurrence of fireflies in an urban locality of Bongaigaon, Assam, India, and to establish preliminary information for future monitoring. Visual Encounter Surveys (VES) were conducted over 30 consecutive evenings from 25 March to 23 April 2026. During each evening, the entire study area was surveyed for approximately 4–5 hours, and the date, time of detection, number of individuals observed, lighting conditions and prevailing weather conditions were recorded. Opportunistic photographs were obtained without capturing or handling individuals. Fireflies were detected on 12 of the 30 observation evenings, with a total of 19 individuals recorded. The highest daily count was three individuals, recorded on 1 April and 16 April 2026, while most detections involved one or two individuals and occurred between 7:00 and 10:00 pm under field-observed low-light conditions. The photographed individual was tentatively identified as Asymmetricata sp. based on external morphological resemblance to Asymmetricata circumdata; however, species-level confirmation was not possible from the available photographs. The observations provide a preliminary occurrence record of fireflies from the study locality and contribute baseline information for future monitoring in an urbanising landscape. However, the short sampling period, single study locality, absence of historical baseline data and reference sites, and lack of quantitative measurements of artificial light, habitat alteration and other environmental variables prevent assessment of population trends or causal attribution to ongoing construction. Long-term, multi-season and replicated monitoring incorporating standardised survey effort, quantitative habitat and light measurements, detailed environmental observations and improved taxonomic documentation is recommended to determine temporal patterns and potential environmental influences on firefly occurrence in Bongaigaon and the wider Northeast Indian region.