Contact and Spatial Repellency of Natural and Synthetic Repellents Toward <i>Dermestes maculatus</i> (Coleoptera: Dermestidae) Beetle Larvae

Dermestes maculatus , commonly known as the hide beetle, is a species of dermestid beetle notorious for its destructive behavior, making it a threat to wool fabrics, leather, and other animal‐based materials often found in museum collections. The use of chemical insecticides requires that the individual get in contact with the treated substrate, with the undesirable potential consequence of the previous irreversible damage. So, the use of repellents is a convenient approach to avoid insect feeding. By contact, the synthetic N, N‐diethyl‐m‐toluamide (DEET) (64.5%) and the natural oils citronella (65.5%) and Manuka (71.4%) elicited significant repellent response ( p = 0 &lt; 0.001). However, the synthetic IR3535 (52.64%) did not demonstrate a significant repellency effect at the same concentrations. In spatial repellency evaluation, DEET (62.1%), citronella oil (81.4%), and IR3535 (64.8%) demonstrate effective repellent effect properties ( p = 0 &lt; 0.001); in contrast, Manuka oil (46.5%) shows no notable effect. For practical applications, essential oils have significant volatilities and must be formulated in slow‐release polymers that modulate their release rate for long periods of time. The lack of correlation between repellency and locomotor activity suggests that repellents primarily trigger sensory‐mediated avoidance rather than generalized agitation or neurotoxicity. The divergence in repellent performance underscores the need for context‐specific applications, that is, contact‐active repellents (DEET, citronella, and Manuka oil) are ideal for direct treatment of vulnerable materials (e.g., wool and leather) where larval feeding occurs while vapor‐active repellents (DEET, citronella, and IR3535) are better suited for area‐wide protection. In all cases, the repellents must be formulated in order not only to prevent their fast evaporation but also to avoid direct contact of harmful liquids with valuable wood or leather goods.