eeiko321

thats right

what ive read about it is......
the disadvantages of Chemical insecticide is that its quickget to the bottom of things straight away basically. disadvantages is that some trees or plants dont cope well to this. e.g chinese elm.

the predator insecticides e.g mantis or lady bugs. the advantages is that you wont have to spray all year round, it benifits more in greenhouse situations indoor where they cant fly off or in large crop areas. disadvantages, like if u only have a few trees...say under 30 or 40 its probably not worth it. they are expensive. and also like rockm said, u gotta keep the "balance" in nature. if all pests are gone, then predators eat themselves (mantids are cannibals also) or they fly off to someone elses garden. you always have a controlled no# of predators in ratio with the pest, so the pests can produce enough to keep your predators around.

hope it helps anyway...
if you dont have a nursery sized garden its probably better to just use insecticide sprays