What does an entomologist study?

Insects - and it is the largest possible subject in zoology. Around a million insect species have been described, estimates of the true total run into the millions, and roughly one in four known animal species is a beetle. Entomologists deal with the majority of animal life on Earth.

The work is mostly not about insects for their own sake. Insects pollinate a large share of the crops people eat, decompose almost everything that dies, and carry the diseases that have killed more humans than any other cause - malaria alone is thought to have killed a substantial fraction of everyone who has ever lived, and it arrives on a mosquito. Forensic entomology can establish time of death from which species have colonised a body and at what stage.

The current concern is that there are measurably fewer of them. A study of German nature reserves published in 2017 found flying insect biomass down by more than 75 per cent over 27 years, and other studies have found comparable declines elsewhere while some have not. The data are patchy because nobody was systematically counting insects decades ago, which is itself the problem - the baseline for the most numerous animals on the planet is largely missing.