parasite has definitions from the field of biology
1
[ noun ] (biology) an animal or plant that lives in or on a host (another animal or plant); the parasite obtains nourishment from the host without benefiting or killing the host

Used in print

(B. J. D. Meeuse, The Story of Pollination....)

The only exception to this is certain bees that have become parasites .

Some members of the bee family have become idlers , social parasites that live at the expense of their hardworking relatives .

The female parasite spends much time in her efforts to find a nest of her host .

2
[ noun ] a follower who hangs around a host (without benefit to the host) in hope of gain or advantage

Related terms

follower mooch

*