Since the beetle escapes from him by flying, it is possible that it is one of Verne's "scholar's jokes" (that is, a joke which only a scientist may recognize; see the entry Jules Verne) (Neff, 1978).
The escape of the beetle through flight is a possible explanation for its being one of Verne's "scholarly jokes," which are jokes understood only by scientists, according to Neff in 1978.