The largest known insect egg is that of the Bolboleaus hiaticollis borer beetle. Its width is approximately the nail of a little finger. The smallest egg is attributed to the Platygaster vernalis wasp and measures half the width of the thinnest human hair recorded.
A team of researchers from Harvard University have found eight different sizes of insect eggs and a fascinating variety of shapes, enough to create a database of nearly 10,500 egg descriptions of some 6,700 species of insects. In a separate analysis, the researchers determined one of the factors that help explain, at least in part, this diversity with which they have evolved is the place where insects lay their eggs, for example, in water or in bodies of other creatures The database and the study have been published in Scientific Data and Nature, respectively.
Eggs offer valuable information about the evolutionary and ecological process of animal reproduction. Mary Stoddard, a biologist at Princeton University, published in 2017 a similar work with 1,400 species of birds. He was able to capture more than 47,000 images of eggs, from which he found a link between its shape and the bird’s ability to fly. “Some insect eggs are spherical or elliptical, but others resemble arrowheads or hot dogs.”
To compile the database of insect eggs, the researchers developed computer programs that extracted measurements of the eggs from the text and photos in 1,756 digitized publications, and then used the measures to estimate the sizes and shapes of the eggs. Representatives of more than 500 families of all insect orders were included.
The evolutionary and development biologist at Harvard University, Cassandra Extavour, co-author of both articles, says that eggs, being only individual cells without complex characteristics that could complicate comparisons, are a great starting point to study how they develop the insects.
According to Samuel Church, an evolutionary biologist at Harvard University, the largest tend to settle on the ground or under leaf litter. His phylogenetic and statistical analyzes have broken several previous hypotheses, such as the idea that larger eggs were elongated to facilitate the female’s expulsion. The team considers that the key is in the place of the putting. “Eggs placed in or on water tend to be smaller and rounder, while those that are inside another animal tend to be smaller and asymmetrical, with one end reaching more than one point than the other. Eggs deposited on the ground or in litter tend to be larger.”