Cover Picture and Issue Information

Insect sperm enter the egg via microscopic structures on the outer eggshell called micropyles, such as those pictured on this wood tiger moth egg ( Arctia plantaginis , Credit: Sarah Aldridge). Micropyles are very diverse and they vary in number, arrangement on the egg surface, and design. Iossa 2022 (doi/ 10.1111/1365-2435.14023 ) collated micropyle data on over 600 insect species from published studies. Following this, Iossa then matched micropyle data on presence and number to temperature, rainfall, and extreme weather for the species in the dataset. Analyses considering phylogenetic relationships across insects showed that primitive insects were more likely to have one or two micropyles, and that the number of micropyles varied greatly across different species–from no micropyle in small leaf‐litter insects, to over 100 on average for bees. Larger eggs tended to have more micropyles than smaller ones, and insect eggs had either few larger micropyles, or numerous smaller ones. Finally, eggs developing in drier environments tended to have fewer micropyles. Altogether, this evidence points to micropyles having not only a function in egg fertilisation, but also in the survival of the embryo in the external environment.