Six 'nationally rare' insect species are among 27 of 'conservation concern' found where a multi-million pound junction revamp on the A47 and A11 is planned.
Plans for the overhaul of the Thickthorn Interchange, used by thousands of people every day, were lodged by Highways England at the end of March.
Proposals include a new slip road off the A11 northbound, before Thickthorn Roundabout, which will take motorists beneath both roads before rejoining traffic on the A47 heading towards Great Yarmouth - eliminating the need to use the roundabout.
The changes would also see a segregated left-hand turn added to those travelling eastbound on the A47, a new footbridge and a fourth lane on the southern part of the junction.
And documents lodged by Highways England have revealed surveys carried out last year found six species of insect, categorised as nationally rare, in the area.
They were among 27 species of insect of "conservation concern" out of 502 found by Abrehart Ecology Limited during a survey commissioned by Highways England.
The nationally rare species included three beetles. They were the carabid beetle (Omophron limbatum), the hornet rove beetle (Quedius dilatatus) and throscid beetle (Aulonothroscus brevicollis).
Two species of rare solitary wasps were found. They were the five banded weevil wasp (Cerceris quinquefasciata), classified as a UK Biodiversity Action Plan priority species because it is so under threat, plus the cuckoo wasp (Hedychrum niemelai).
A single tachinid fly (Cistogaster globosa), which the survey's author Dr Ross Piper describes as "a distinctive species unlikely to be overlooked and probably genuinely rare" was also found.
The bulk of the area is agricultural land, but veteran trees which are decaying, along with botanically rich grassland, form habitats for insects.
Dr Piper said the most valuable habitats - the old and ancient trees and the grassland - should be retained and buffered.
And he advises: "Some areas of more valuable habitat will be lost, but, on the whole, this can be compensated for by the
creation of new habitats.
"The entire length of the proposed new road could be designed with nature in mind to create a ribbon of valuable habitat through the landscape."
He said a well designed and executed scheme could be "considerably better for wildlife" than the current agricultural landscape.
As previously reported, Highways England will need to obtain a licence to relocate water voles in the area, should the changes go ahead.
The Planning Inspectorate will hold an inquiry before making recommendations on whether the changes should be permitted.
Transport secretary Grant Shapps will then decide whether to allow it or not.
The mooted revamp is part of a £300m raft of changes to the A47 between Great Yarmouth and Peterborough.
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