Longest lifespan for an insect

The longest-lived insects are the splendour beetles (Buprestidae). On 27 May 1983 a specimen of Buprestis aurulenta appeared from the staircase timber in the home of Mr W. Euston of Prittlewell, Southend-on-Sea, Essex, UK, after at least 47 years as a larva. All sources quote that Buprestis aurulenta requires 1-3 years to complete development but that in buildings egg to adult development may be prolonged to 30–50 years! The adult of the species is around 2cm long, and lives around 2–3 months.