The communist plot isn't so much the invasion, IMO, nor is it coming from the invaders. The communists are co-opting the issue. It's the rallies, the "uniting workers to the struggle" and the overall mayhem they can create.
The communists, leftists, anti-Americans will take over any issue if they can gain more followers to their cause and try to create chaos in this country.
Let me add one other thing. It's not the illegal Mexican picking the peaches who said to himself, "We ought to go on strike for a day" (or however you say that in Spanish).
If you look on these websites, the people putting the sites together and organizing the rallies even acknowledge in some instances that they are not immigrants (read white-bread trust fund leftists).
How does Jose the gardener get tied up with the anarchist movement when he creates his pro-rights for illegals website?