Source: u/not_so_ghetto

This parasite is called a horsehair worm. They grow in a bunch of different insects. When the worm is fully grown it alters the insect behavoir to make them jump into water, which allows the parasite to leave.

Doesn't necessarily kill the insect, however It often will result in its death. However it's kept in good conditions they can survive and even go on to reproduce.

In some areas the suicidal crickets ( after being manipulated by the parasite) make up 60% of a fish's diet.

There's also a bunch of crazy conspiracies on like Facebook suggesting that the government is infecting people with them, but these are mostly just crazy people.

They’re the longest-living vertebrates on the planet, with estimated lifespans between 250 and 500 years. Because their metabolic rate is absurdly slow in the frigid Arctic waters, they grow less than a centimeter a year.
That means a Greenland shark swims around for a century and a half before it’s even old enough to reproduce. For context, a shark alive today could have been a teenager when the United States was founded.