That means it is likely to be a busy year for EdJohnson, director of science at the Staten Island Museum, which, with about 35, 000 specimens, said it boasts the largest cicada collection in North America.
If so the unions, who help to choose the party's leader, could vote to install a favoured candidate, such as Alan Johnson or Ed Balls, both union-friendly cabinet members.
Mrs Lawrence was joined at the event by relatives, friends and senior political figures including Prime Minister David Cameron, Deputy Prime Minister Nick Clegg, Labour Party Leader Ed Miliband and London Mayor Boris Johnson.