The World's Biggest Bug is a Grub

270 Wh a t , e x a c t l y, i s the world’s largest insect? Most introductory entomology courses probably report that it is “the Goliath beetle of Africa,” and that is the answer you get from the ever-popular Guinness World Records as well. A variety of scientific names are given for this beast, but according to the last professional revision of the genus, by J. T. Wiebes of the Leiden Museum (1968), all the really big Goliath beetles should be classified as subspecies of Goliathus goliatus (yes, without an “h” in the specific epithet, and including G. g. regius, G. g. orientalis, and the like). I personally love these beetles and have since childhood, and I am currently rearing them for study as well. That’s why it’s so painful to admit that they are actually not the world’s largest insects. Among beetles, according to the online “University of Florida Book of Insect Records,” three general sorts of critters more or less tie for the title of heaviest: Goliath beetles, two species of Megasoma rhinoceros beetles, and the huge longhorn beetle Titanus giganteus. All appear to be capable of attaining an adult weight of 45 g, at least as maximum-size males. It turns out, however, that entomologists are not terribly interested in weighing live bugs; they are much better at measuring how long they are once they are dead. Thus, the 45-g figure comes from guesstimates and extrapolations, not from real measurements, reported in the real literature, made by real entomologists with real equipment and real beetles. I can tell you, from my own work, that a 70-mm male Goliath weighs about 22 g when it first emerges from the pupa, but only 14 g once it voids its meconium (the waste products left over after metamorphosis). Even after months of feeding, the weight does not increase after that. This makes it difficult to believe that a full-sized, 11-cm male would weigh 45 g, but not impossible, I suppose. As of now, the one and only quasi-reliable figure is a weight of 42 g for a 10 cm male G. goliatus goliatus, which was wildTERMINAL SEGMENT