The scourge of the well kept lawn! In reality it's the scourge of the "not Well Kept" lawn. A well kept lawn that has it's soil properly aerated, is well fed and watered and cut to the correct height will usually take care of the weeds on it's own! This is especially true of the grasses that spread via rhizomes and develop a thick interlaced mat. When at their peak they are very competitive and will typically choke out most weeds before the get a foothold. Hey areas to consider for natural weed control:

Mowing - Aside from mowing the weeds keeping your grass at the correct height will help control weeds from growing by shading the "weedlings". Mowing frequently will also remove the seed heads from weeds, keeping them from developing and spreading themselves.

Soil quality - Aeration and Proper fertilization will create an environment that is friendly to your lawn grass but discourages weed growth. If you follow good watering, cutting and feeding practices you should have minimal problems with weeds.

However, If you have a serious weed problem and are inclined to do so you can use herbicides and pre-emergents. Herbicides are available as stand alone products as well as in Weed and Feed type products (as are the pre-emergents). Although convenient the multipurpose products sometimes are not desire able as the right time to apply herbicide or pre-emergent may not coincide with the best time to apply fertilizer.

There are a variety of herbicides and pre-emergents available, Ideally you should identify the weeds that you are targeting and base your decision on which of these to you based on manufacturers guidelines.

I have found an excellent reference source of information on This Old House . They have information on identifying the weeds that you may have and links to manufacturers of various weed control products which are well organized.

There are a number of insects and grubs that can affect your lawn and quickly turn a beautiful lawn into a patchwork of browns pots. My preference on insect control is a spray application every 4 to 6 weeks starting in the late spring. I believe that a granular application is more effective but the liquid application is generally more economical. We keep dogs as well as cats so I am always careful to make sure that the insecticide I apply will work on ticks and fleas as well. Since I generally apply insecticide to prevent fleas and ticks on our animals I seldom if ever see any damage on my lawn.

If you don't use an insecticide like I do you need to know what to look for on your lawn before treating it. Wilted, Dead or dying grass would probably be caused by soil inhabiting insects, white grubs and mole crickets are an example of these. Grass that appears to have been cut off close to the ground is most likely caused by thatch inhabiting insect such as cutworms, armyworms, and sod webworms. Other thatch inhabitants such as cinch bugs and spittlebugs may cause damage of dead or wilted grass, similar to soil inhabiting insects.

Here is a link to a guide that helps in the identification of these insects. Luckily most of the insecticides available for lawn use or broad spectrum, the concentration varying depending on the pest you are trying to remove. So choosing an insecticide shouldn't be too difficult to overcome any infestations that you may have. Please read the manufacturers recommendations and follow them carefully!