The National Planning Policy Framework (NPPF) unveiled today, has championed "robust protections" for the countryside but our urban areas also boast key wildlife habitats.
Existing planning guidance has been built up over many decades to reduce the harm that new developments have on the environment.
Along with other wildlife NGOs, Butterfly Conservation believes that they had successfully ensured that developments were more sustainable and were not hindering growth.
Butterflies and moths are among the most rapidly declining wildlife groups in Britain, so any weakening of planning rules will make it far more difficult to halt their decline and meet the internationally agreed targets to halt biodiversity loss by 2020.
Breeding habitats in and around urban centres provide important green space for people as well as refuges for wildlife.
Dr Martin Warren, chief executive of Butterfly Conservation said: "We welcome the commitment to sustainable development but the devil will be in the detail.
"The "brownfield first" presumption also represents something of a concern as brownfield sites are often important habitats for insect species including butterflies and moths.
"The new regulations could lead to a further spate of habitat loss around our urban areas, leaving them as deserts for wildlife.
"We are calling for a more imaginative approach to urban developments that incorporate green spaces, making them more attractive to people as well as wildlife."