In the scientific study of animals, and insects, vampirism is also used in reference to mosquitos, leeches, vampire bats, of course, mistletoe, and other parasitic creatures surviving on tissues and fluids of other living creatures. Blood is a tissue fluid; just like the meat that other animals feed on, as well as human being, blood is rich in proteins, and lipids. Many smaller animals and insects, as well as worms, have evolved to a point where feeding off of the blood is preferred, or even essential to their survival. Sometimes, this can become a harmful process; such as with mosquitoes that spread malaria. Other species, such as vampire bats, who rarely spread disease, or leeches which will cleanse the blood, and are used for medical purposes, –are neutral, and can even benefit mankind.
An example of an animal with the obligatory need for blood is the assassin bug, found in South America. They insert a needle-like proboscis into their prey, –other insects, such as cockroaches and beetles, –and it liquefies their insides, so that the assassin bug can drink them, with its very own built in straw. It’s mainly thought to be beneficial, and is kept as a pet for insect control. However, if owners do not handle the insect carefully, they may be bitten, and the bite is said to be extremely painful. Also, there is a minimal risk of being infected with a potentially fatal illness called “Chagas disease.” If the assassin bug is indigenous to your area, it’s best to leave it alone.
An example of the optional need to drink blood is the mosquito. That’s right! Those horrible little creatures can feed off of pollen, fruit juices, and other biological liquids (some really, really gross ones too) that are not blood. Also, sometimes only the females will drink blood, since its essential for her reproductive system. Other examples of blood drinkers found in nature are nematodes, and other creepy crawlers, such as parasitic worms, found in human and animal intestines.