 When the larva attains its maximum size , it pupates and undergoes metamorphosis . It makes a globular cocoon of sand stuck together with fine silk spun from a slender spinneret at the rear end of the body . The cocoon may be buried several centimetres deep in the sand . After the completion of its transformation into an adult insect in about one month , it emerges from the case , leaving the pupal integument behind , and works its way to the surface . After about twenty minutes , the adult 's wings are fully opened and it flies off in search of a mate . The adult is considerably larger than the larva and antlions exhibit the greatest disparity in size between larva and adult of any type of holometabolous insect ; this is by virtue of the fact that the exoskeleton of the adult is extremely thin and flimsy , with an exceptionally low mass per unit of volume . The adult typically lives for about 25 days , but some insects survive for as long as 45 days . 
