The giant tachinid fly (Tachina grossa) is the undisputed heavyweight of European flies, reaching an impressive length of up to 2 cm. While it mimics both the appearance and the heavy, buzzing flight of a bumblebee to deter predators, it is entirely harmless. Its reproductive cycle, however, is a masterpiece of macabre specialization: females deposit their eggs onto or directly inside large, hairy caterpillars. Upon hatching, the maggot burrows into its host, methodically devouring non-vital organs from the inside out to keep the caterpillar alive and fresh until the very last moment. As adults, these awesome flies leave their gruesome youth behind; they spend most of their time basking in the sun and visiting a wide array of flowers to feast on nectar and pollen, making them highly effective pollinators and vital natural pest controllers. I crossed paths with this magnificent female during a walk through a forest close to my home in Järfälla, Sweden. 🙂