Caught in the act of hatching – a group of heteropteran nymphs escaping from their eggs preserved in Dominican amber

Abstract

Insects enclosed in amber can provide unique insights into the morphology, but also behavioural aspects of extinct species, due to their often exceptional preservation. This is especially true in the cases of so-called ‘frozen behaviour', were animals were caught in the fresh and viscid resin while e.g. mating, egg laying, capturing prey or in rare cases, hatching. Here, we report a group of heteropteran insect nymphs preserved together with their eggs in 15–20 million-year-old Dominican amber. Two of the nymphs were caught in the act of hatching. The eggs form a cluster of 47 individuals and possess a morphology, as occurs in the eggs of some extant Reduviidae, especially Hapactorinae. Most notable are the operculum surrounding elongated extensions of the chorion at the apical part of the elongated eggs. The cluster strongly resembles the appearance of a composite flower. Details of the egg morphology of extinct insects are very scarce, and even if fossil remains can be identified as insect eggs, the corresponding insect group can rarely be determined. Rare cases of ‘frozen behaviour’, such the herein described, allow to observe aspects of the hatching process, but can also help to shed light on the morphology of the eggs from different extinct insect groups.