One thing that I like to emphasize is the usefulness of beneficial insects and other creatures. There are a great many small predators that eat our insect pests and we must promote their welfare so that we have a healthy garden. I've noticed too many times that people want to use beneficial insects but end up getting impatient and using pesticides to control the pests which of course then kill the beneficials as well.
Here are a few of the most common benefials that I recommend.
Lady bugs aka Ladybird Beetles - Coccinella
Adult Seven Spotted Ladybird Beetle
The majority of coccinellid species are generally considered useful insects, because many species prey aphids or scale insects. Many coccinellids lay their eggs directly in aphid and scale insect colonies in order to ensure their larvae have an immediate food source.
Mealybug Destroyers -
Cryptolaemus montrouzieri
Cryptolaemus montrouzieri, common name Mealybug Ladybird or Mealybug Destroyer is a ladybird species endemic to Queensland and New South Wales, Australia. Unlike many of the often brightly coloured Coccinellidae, it is predominantly brown and has no spots. It has been used as a biological control agent against mealybugs and other scale insects. As a larva it apparently looks like the mealybugs they prey on, which is called aggressive mimicry.
Parasitic Wasps
These tiny, non-stinging wasps are some of the most beneficial insects in the garden and are known to parasitize over 200 species of pests. Though there are many different species of parasitic wasps, they all work by preying upon one or more pest insects. They lay their eggs inside the pest larvae and the wasp larva eats it from the inside, out.
Decolate Snails (Rumina decollata)
This species was introduced from the Mediterranean into southern California in the 1970s to help control the brown garden snail (Helix aspersa). Each decollate snail lays about 500 eggs during its lifetime. The snails live in litter on soil, emerging to feed when it is dark and damp. They feed mostly on other snails and decaying organic matter. Decollates also eat young seedlings, so it may not be desirable to release them in gardens. In citrus, establishment and proper maintenance of decollate snail populations has been shown to permanently reduce brown garden snail populations to insignificant levels in 4 to 10 years. The best time to introduce and establish decollate snails in California is during warm, damp weather in the early spring. Introductions of this snail are permitted only in certain San Joaquin Valley and southern California county locations (they are illegal in other areas as they may affect native snail and slug populations).
Praying Mantis (Mantodea)
Mantises are mostly ambush predators, but a few ground-dwelling species are found actively pursuing their prey. They normally live for about a year. In cooler climates, the adults lay eggs in autumn then die. The eggs are protected by their hard capsules and hatch in the spring. Females sometimes practice sexual cannibalism, eating their mates after copulation. Mantises are among the insects most commonly kept as pets.
Beneficial Nematodes
Nematodes are tiny, un-segmented wormlike animals found in soil all over the world. Scientists think there are about half a million different species of nematodes. Some are crop pests, while others are crop protectors. Beneficial nematodes are valuable because they cause disease in destructive bug pests, but don't harm humans, other animals or the environment.
Nematodes enter pest bugs while they are still alive, then they multiply inside the bugs (which eventually die) and finally burst out of the dead bodies. The number of nematodes inside a single bug (depending on the species) ranges from 10,000 to 500,000. Although you can barely see one young nematode with your naked eye, large groups of these tiny wigglers pouring out of the dead insects are easy to see. Then the nematodes wriggle off to find other insects to "invade," starting the whole cycle all over again.
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