First of all you need to identify what kind of insects you have or are likely to get. There are plenty of common species, but only a few of these do any significant harm in a given area ? and there are a number of ways to identify them.

Check plant leaves, flowers and shrubs and match any you don't recognise against photos you can find on the internet. Look for information on any particular plants that you're concerned over and you shouldn't have any trouble identifying the most common pests. Oftne that information will contain a photo you can use for comparison.

A lot of the insects on flowers, trees, grass and other plants are hidden and you may have to rely on guesswork and apply general methods that are used to control common invasive species. Aphids are often found on rose bushes, for example but may be difficult to spot. Grass often has grub infestations that is not visible to the eye and can only be detected by looking underneath the soil.

Another method is to examine any effects you might see

Grass with round, brown spots, especially in late Spring through Summer may mean you have a Japanese Beetle grub problem. Double check your guesswork with other methods if you find that patches of grass come away from the soil easily like carpet with loose tacks then you may have a grub problem.

Eliminating insects and grubs that are causing problems is usually safe, cheap and easy especially with modern control methods. This doesn't mean you have to purchase and spray large areas with chemicals, although most of them are said to be safe for both humans and the environment.

Instead of using grub killing fertilizer or insecticide use biological control methods. These are considered to be more organic and are becoming more popular and effective all the time. A substance called ?milky spores? can be a very cost effective way to control grubs in lawns.

Biological control may be more expensive than a bag of grub insecticide to start with. A 30lb bag of grub killer may cost $10 and last two years where a 1-liter bottle of milky spores may be $30 or more, but it lasts for 10 years. This works well because it is a natural compound which contains living organisms that invade the grub larvae and interrupts their growth cycle. In effect, you have one organism killing another. The spores are harmless to your lawn as they only act on the grub.

There are other control methods like the one above each meant to solve a particular problem. This is because organisms are particular about which insects they will invade and when. These methods are safe, cost effective and many are last longer than other, chemical methods.

You can use chemical insecticides if you really need to do so. Modern insecticides are much more sophisticated, and decay safely and quickly into harmless byproducts without harming the environment. They also do the job before they decay.