In an article about the new Pew Hispanic study showing that the illegal alien population in the U.S. has decreased over the past decade comes this:

...Los Angeles County officials said they have actually seen an increase in the costs of providing services to undocumented immigrants and in the number of citizen children of undocumented parents receiving Food Stamps and welfare benefits.

The amount of money the county spends on health, welfare and criminal justice services for undocumented immigrants increased from $1 billion in 2008 to $1.4 billion in 2009, according to figures provided by county Supervisor Michael D. Antonovich. By including the education costs for the children of undocumented immigrants, Antonovich's spokesman, Tony Bell, said the annual costs now exceed $2 billion.

...From January to July, the number of citizen children of undocumented parents receiving Food Stamps in the county increased 4 percent from 103,238 to 107,504, according to the Department of Public Social Services.