Many complementary insecticides such as Organophosphate and Carbamate have half lives of only a few days to several weeks, are not fat soluble, and are often much more specific in the targets they affect. While these insecticides do not accumulate up the food chain and are safer environmentally, they are very soluble in water and usually quite toxic to fish.
In contrast, most herbicides currently in use break down by the end of the growing season and are relatively less toxic to fish than insecticides. However, if herbicides reach surface waters, many species of aquatic plants can be killed. Along with shorter half lives, newer pesticides utilize more effective stickers (the chemical which keeps them in place) and are thus effective in much lower concentrations. This makes them easier to control and adds less chemical to the environment. In addition, biological controls (viruses and bacteria that occur in nature) are being refined and adopted for use as natural microbial pesticides, such as Bacillus thuringiensis for the control of gypsy moth.