just within the last week, i’ve come across three blister beetles (meloidae) – oil beetles (meloe proscarabaeus; schwarzblauer ölkäfer), to be specific.
oil beetles are very rare, and are protected in austria.
distinguishing the gender is apparently pretty easy: males have a sharp bend in their antennas, females don’t. see here!
if the adult beetle is bothered, it can excrete a substance that contains cantharidin from its joints. cantharidin is a poison that can even be dangerous to humans (but is also used for medical purposes).
in last photo, you can see an orange droplet of poison on a beetle’s joint. before i noticed this bug, tiger thought it would be a fun thing to play with…
their life cycle is pretty interesting, too: females lay several thousands of eggs, and it takes up to a year for the larvae to hatch. as soon as they leave the eggs, each one craws up to a flower and waits for a solitary bee to stick to. the larva stays on its “taxi” until the bee lays an egg – now it gets off and eats the egg and honey, and after some time buries itself in the ground again, where it forms a pupa and will hatch the following spring.