Factors contributing to the decline of an endangered flightless longhorn beetle: A 20‐year study

World‐wide decreases of insect abundance and diversity are of major concern because of their importance for ecosystem functioning and the stability of ecosystems. Various studies reported dramatic declines of butterflies, wild bees and beetles in agricultural areas. Yet, evidence for decreasing abundance in cryptic insect species is scarce. Using a transect‐count technique, we monitored the relative population size of the endangered flightless...