Vampire Bats (2005) on Netflix

Plot summary

Maddy Rierdon has traded her post as an insect specialist for the USDA for a college classroom in Louisiana, where she lives with her husband, Dan Dryer, and their two daughters. Then deer and other animals turn up drained of blood, and one of her students is chased through the forest and killed the same way. Police arrest two of his friends, and Maddy sets out to prove them innocent. Her inquiries tell her the attacker moves in a pack and is fast. When two fishermen die on their boat and traces of bat droppings are found at the scene, the police come to believe bats are behind the deaths.