If you have a St. Augustine lawn, you may want to take a really close look at the grass near the soil. Chinch bugs (Blissus insularis Barber) can do a lot of damage in a short amount of time, especially when the numbers build up. They are true bugs so they have piercing-sucking mouth parts that cause all the damage.
They can typically be found at the soil line. Getting down on the ground and looking through the base of the plants is one way to look for this pest. It is very small with the adults being about ¼ inch long and black and white in color. The immature stages look very similar to the adults but much smaller.