Why are they so sticky?

When Seth Brundle makes a huge scientific and technological breakthrough in teleportation, he decides to test it on himself. Unbeknownst to him, a common housefly manages to get inside the device and the two become one.

Test space rockets exploding at liftoff and increased reporting of UFO sightings culminate in a direct attempt by alien survivors of a dead, extra-galactic civilization to invade Earth from impervious flying saucers, using ray-weapons of mass destruction.

In Arborville, California, three high school students try to protect their hometown from a gelatinous alien life form that engulfs everything it touches.

A drive-in favorite, this sci-fi classic follows teenagers Steve and his best girl, Jane, as they try to protect their hometown from a gelatinous alien life form that engulfs everything it touches. The first to discover the substance and live to tell about it, Steve and Jane witness the blob destroying an elderly man, then it growing to a terrifying size. But no one else has seen the goo, and policeman Dave refuses to believe the kids without proof.