Garden pests have evolved over eons developing from one, or maybe more, insect species into many. They get a start in your garden when an adult insect lays eggs on plants and those eggs hatch. Some insects are more destructive in the larval stage than as an adult. There are, however, many more beneficial insects out there then pests and they can aid in controlling the pests.

Go to the forum entitled Integrated Pest Management, B.Shah.

In nature there are few true pests because most organisms have functions in the particular natural environment. Humans come in with plants often not native to the region, often true cultivars that can't survive in the wild. You might say they are ecologically and genetically weak and need human protection to greater or lesser extent to be grown successfully.

Here is a link that might be useful: forum on I.P.M.

Your pest is not necessarily someone else's pest. There is a plant called butterfly weed. It happens to attract butterflies, which some people like, but it is ugly, which some people don't like; so it got that name. It also happens to attract aphids. Well if it's ugly and attracts aphids, who cares about the plant? Let's call it a pest.

Down here people plant butterfly weed to attract butterflies and aphids. The reason they want to attract aphids is that the lady bugs and other beneficial insects come to the garden to feast on the abundance of aphids. When they are left alone, the beneficials overpopulate on the supply of aphids and extend their range to the rest of your garden. So the butterfly weed is planted to attract beneficial insects to the garden.

An old gardener once asked me, "How do all the bugs make straight for my plants?" In many cases they come right from your own garden. For example, Colorado potato beetles over-winter in adult form in the soil right where they dropped off your potatoes the previous year. And if you didn't grow potatoes the previous year, beetles from your neighbours' gardens will find your potatoes. Their antennae can detect their favourite food (or a potential mate) from half a mile away. Squash vine borer moths behave similarly. The good news is that carniverous insects behave in the same way. For example, your mulch of chopped leaves is a perfect habitat for slugs. It's also a perfect habitat for ground beetles who -- both adult and larva -- specialize in eating slugs. I hope this responds to your question, which -- you must admit -- was somewhat ambiguous. Regards, Peter.

shahwin: what is the reason or context for your question by the way? Regards, Peter.