designs outside the home

It's quite common to see fairly elaborate designs just outside the home. They might be outside an apartment, but inside the building, or outside a house. Often they are done in white, but on the morning of the new year of 2008, many houses in the neighborhood had much larger designs that extended into the street with all kinds of colors and with words added such as Happy New Year 2008. It seems there's usually someone in the household who takes this on because she loves doing making these symmetric designs. I didn't get a photo of the colorful ones because the camera wasn't working for a few days. One girl aged 19 was very proud of her New Year's design; it took her until 4:30 in the morning to finish it, then she slept until she had to get up about 7 a.m. to go to work. January 1 is not an official holiday in India.

This design was outside a home that was on an alley just across from a tailor's shop. The story I heard on the origin of these designs is: before walkways and streets were paved, it could get quite dusty outside the home. To prevent dust from being walked inside, cow dung (which I was told does not harbor bacteria) was spread over the dirt. Then a design was made on it using rice powder. This rice powder was an offering for the ants. If they fed the ants on the outside, they might be satisfied and not come in the house. These days, the cow dung step is skipped, at least where there's concrete.
If someone knows more about this tradition, or if I got something wrong, please comment.