Eggcelent strategies! Egg Production, Egg Morphology and Laying Behaviour of Insects preserved in Amber from the Cretaceous to the Miocene

Extant insects are adapted to a wide range of habitats and lifestyles on account of numerous specific strategies. In addition to foraging, defence and camouflage, reproduction is one of the existential determinants. Within insects, not only mating strategies are diverse in order to increase the chances of survival of the offspring, but also all aspects regarding the egg: the production of eggs, morphology and laying behaviour.

The number of eggs in a clutch, their size, shape and surface structure as well as the placement of the egg and the parental care after laying are often very characteristic of certain insect groups or species. However, when an isolated egg or clutch is observed, it can be difficult to identify the specific producer, even in extant insects because necessary information is missing in the literature.

The identification of the producer of a fossilised egg is even more difficult, which is further aggravated by the fact that insect eggs are rarely found in the fossil record in general and in amber in particular. The reasons for the rarity of eggs lie in taphonomic aspects, which depend, among other things, on the delicacy of the eggs and hidden deposits under bark or under the ground that were inaccessible to resin.

We present insect eggs and clutches preserved in amber from the Cretaceous to the Miocene and discuss aspects of the evolution of egg production, egg laying and egg morphology strategies. We also illustrate how knowledge about fossil eggs in amber can be expanded.