Like the vermin that will inevitably invade your premises, illegals are looking for a means of survival. They are destitute and are willing to exploit the circumstances that would allow them to feed on your scraps. Sadly, the analogy breaks down beyond this point.
The crumbs attracting aliens are jobs that guys just like 19-year old Q-Tip and Shaheed Muhammad could do to lawfully earn a living, as well as the social services many of their neighbours back in inner city New York may rely on. Additionally, in places with an abundance of Spanish speakers, not being fluent can become a handicap for those seeking even entry-level positions.