They grab the colonists, they move them over there and they immobilize them to be hosts for more of these.
7 seconds sound clip from the Aliens (1986) movie soundboard.
You can hear this line at 01:34:49 in the Blu-ray version of the movie.
Quote context
[...]
- Sneak.
- The molecular acid oxidizes after the creature's death, completely neutralizing it.
- Bishop, you know, that's very interesting, but it doesn't really get us anywhere, does it?
- I'm trying to figure out what we're dealing with here.
- Which would mean that there would have to be a lot of these parasites, right?
- One for each colonist. That's over 100, at least.
- But each one of these things comes from an egg, right? So who's laying these eggs?
- I'm not sure. It must be something we haven't seen yet.
[...]