Modern entomologists are primarily engaged in the research of insects that provide a direct benefit, or cause direct harm, to human interests. The benefits of researching and protecting insect life may be immediate, such as using an insect presence to control pests or diseases, or long-term, such as protecting native species from unnecessary human intercession in order to maintain a balanced ecosystem. Research on harmful insect life endeavors to produce methods of insect control that are reliable and effective, while minimizing the effect of the control on other species. Although most insect orders include both pests and beneficial species, a few orders, such as lice and fleas, provide no benefits to humans and are said to be entirely parasitic.