Potter wasp nests in Cretaceous amber

Nesting behavior represents a pivotal adaptive strategy in insects, providing protective environments for offspring and optimizing resource allocation¹. Among aculeate (stinging) Hymenoptera, the vespid subfamily Eumeninae (potter wasps) exemplifies sophisticated solitary nesting strategies, employing unique mud nest structures and specialized brood care behaviors². However, the evolutionary origins of these complex behaviors have remained poorly understood due to the scarcity of relevant fossil evidence. Here, we report the discovery of fossilized potter wasp nests preserved in mid-Cretaceous Kachin amber (∼99 Ma), providing the first direct evidence of eumenine nesting behavior in the fossil record. These nests exhibit striking morphological similarities to those of the extant species of the tribe Eumenini, including bottle-shaped architecture, mud-based construction, and preserved eggs, demonstrating that nesting behaviors had already evolved by the Cenomanian.