Now let us cross the equator and go right down to the southern hemisphere, to the islands of Mauritius and Réunion: we shall here find not a Sphex, but a closely-allied Wasp of the same tribe, the Compressed Chlorion, hunting the horrible Kakerlak, that ravager of the foodstuffs in the ships and harbours of the colonies. These Kakerlaks are none other than Cockroaches, whereof one species haunts our dwellings. Who does not know the evil-smelling insect, which, thanks to its flat body, like that of a huge Bug, slips at night through the gaps in furniture and the crannies of partitions and invades any place containing provisions to be devoured? This is the Black-beetle of our houses, a disgusting counterpart of the no less disgusting prey beloved of the Chlorion. What is there about the Kakerlak to cause him to be selected as a prey by a near cousin of our Sphex-wasps? It is quite simple: with his Bug shape, the Kakerlak also is an Orthopteron, just as much as the Cricket, the Ephippiger or the Locust. From these six examples, the only ones known to me and of such different origins, we might perhaps deduce that all the Sphex hunt Orthoptera. At any rate, without adopting so general a conclusion, we see what the food of their larvæ must be in most cases. There is a reason for this surprising choice. What is it? What are the grounds for a diet which, within the strict limits of one entomological order, is composed here of stinking Kakerlaks, there of somewhat dry, but highly-flavoured Locusts, elsewhere again of plump Crickets or fat Ephippigers? I confess that I cannot tell, that I am absolutely in the dark; and I leave the problem to others. At the same time, we may observe that the Orthoptera are among insects what the Ruminants are among mammals. Endowed with a mighty paunch and a placid temperament, they graze contentedly and soon put on flesh. They are numerous, widely distributed and slow in movement, which renders them easy to catch; moreover, they are of a large size, making fine heads of game. Who can say if the Sphex-wasps, powerful huntresses, requiring big prey, do not find in these Ruminants of the insect world what we ourselves find in our domestic Ruminants, the Sheep and the Ox, peaceable victims yielding plenty of flesh? It is just a possibility, but no more.