Raccoons typically breed in the months January through March, and it takes a bit over two months before the young are born. So we are at the peak season for young raccoons. However, young raccoons often stay with the female through the fall, and sometimes through to the next spring, despite being able to care for themselves.
By Illinois law, a property owner needs a permit (it is free) from the Illinois Department of Natural Resources in order to trap raccoons. Permits are issued in cases where the animal is causing property damage or is causing a public health or safety concern. Additionally, by Illinois law, raccoons in Illinois must either be: 1) released on the same property within 100 yards of where the animal was captured, 2) surrendered to a licensed veterinarian who is a licensed wildlife rehabilitator, or 3) humanely euthanized. The biologist issuing the permit will determine the appropriate outcome for each case.
Raccoons become quite aggressive when trapped, and it is not recommended that homeowners try to trap the animals themselves. Nuisance Wildlife Control Operators (NWCOs) are licensed by the IDNR, and will humanely trap and remove the animal for homeowners. They charge a fee for this service.
If the only problem that the raccoon is causing is breaking into the garage to eat cat food, there are a couple of solutions to try prior to trapping the animal. First is store the cat food in a solid container that the raccoon cannot gain access to, and to make sure that any entrances to the garage are closed. If there are holes or other damage to the structure, these should be repaired to keep the raccoon out (but make sure there aren't young in the garage, or the female will simply chew and claw her way back in through the repair job to reach her young).
Many people think that the most humane solution when dealing with a wild animal that is not welcome is to trap it and "take it to the country, local forest preserve, etc.". Unfortunately, this is not the quick and kind solution it appears to be. First, as mentioned before, wild animals become aggressive when trapped and may scratch or bite. This is dangerous enough in and of itself, but these animals can also be carriers of disease, some of which are transmittable to people, such as rabies. Second, any diseases or pests that the relocated animal carries have the potential to spread to the new local population which puts other animals, and potentially people, at risk. Finally, the reality is that many relocated animals do not survive. The new location to which the animal is moved will already have a population of animals using the resources (food, water, and shelter) of the area. Relocated animals often travel long distances trying to get back to their home or trying to find a new place to establish a territory. During this time they are more vulnerable to predators and increase their risk of being struck and killed by vehicles. And as you know, if a female is removed without her young, they will be left to starve to death.
If you have more questions, or if you would like contact information for the local IDNR wildlife biologist or for NWCOs providing service in your area, please feel free to e-mail me.