Abstract [AI assisted]

Accurate identification is fundamental to insect recording and conservation, yet many species cannot be reliably identified without temporarily immobilising active individuals. This report briefly reviews the use of carbon dioxide (CO₂) as a practical anaesthetic for insects in field settings, with particular emphasis on humane handling, specimen safety and recorder usability. Drawing on long-term practical experience and recent discussions on insect welfare, the report outlines when and why anaesthesia may be appropriate, explains the physiological effects of CO₂ on insects, and provides guidance on minimising distress and adverse outcomes. Particular consideration is given to dose, exposure time, temperature, and taxa for which CO₂ may be unsuitable. The second part of the report evaluates several portable CO₂ delivery systems, comparing their effectiveness, safety, cost and ease of use for field entomologists. The findings identify suitable current alternatives to obsolete equipment and highlight best practice for controlled gas delivery. Overall, the report presents CO₂ anaesthesia as a valuable refinement for insect recording, collection and public engagement when applied carefully and responsibly.

DISCLAIMER: The recommendations / advice outlined in this external report do not necessarily reflect the views of National Museums Liverpool, and the organisation cannot be held responsible for the unsafe use of CO2 dispensers.

Published 19th December 2025