The Institute of Ecology and Environmental Management's code of professional conduct aims to promote the need to report truthfully and clearly, to convey findings objectively and not to commit scientific fraud.
Dr David Goode, vice president, said legal constraints made it difficult to give specific examples, but those betraying the ethics of the profession had in the past been 'getting away with murder'.
He said it was known who some of the culprits were, and that future breaches of the new code might lead to malpractice procedures.
'This is a serious problem because we are in a rapidly developing profession. We are aware in the institute that things need to be tightened up. We know of the shortcomings of some of the consultants and it is important clients know there is somebody responsible for accreditation and monitoring,' he said.
Common forms of malpractice include accepting a brief to find nothing of value on a site; carrying out a survey at a time of year when it will not be effective, such as a grassland ecology survey in winter when a lot of species of plant would not be visible; ecologists misrepresenting their qualifications; and accepting financial inducements for a particular result.
It is impossible to say how many supermarkets or office blocks have had their paths through the planning bureaucracy smoothed by unscrupulous consultants.
Sue Everett, the institute's development officer, said: 'There has been criticism that some consultants will produce what the developer wants to earn their fee. Our members must also make clear to clients that reports must not be misrepresented or selectively used. Basically, there needs to be a scientific rigour in ecologists' approach.'
She said the institute, which was formed in June last year and has more than 400 members, was concerned that the profession was unregulated.
'It means the unprincipled few have discredited the reputation of the majority.'
The institute hopes to reach a membership of 2,000 and that ecology will be recognised as a regulated profession which maintained high standards.