Male Cockroaches are readily distinguished from the females by the well-developed wings and wing-covers. They are also slighter and weaker than the females; their terga and sterna are not so much thickened; their alimentary canal is more slender, and they feed less greedily (the crop of the male is usually only half-full of food). They stand higher on their legs than the females, whose abdomen trails on the ground. The external anatomical differences of the sexes may be tabulated thus:-- _Female._ | _Male._ | Antenna shorter than the body, | Antenna rather longer than the third joint longer than | the body, the third joint the second. | about as long as the second. | Wings and wing-covers rudimentary. | Wings and wing-covers well | developed. | Mesosternum divided. | Mesosternum entire. | Abdomen broader. | Abdomen narrower. | Terga 8 and 9 not externally | Terga 8 and 9 externally visible. | visible. | The 10th tergum notched. | The 10th tergum hardly | notched. | The 7th sternum divided behind. | The 7th sternum undivided. | The external outlet of the | The outlet between the 10th rectum and vulva between | tergum and the 9th sternum. the 10th tergum and the | 7th sternum. | | No sub-anal styles. | Sub-anal styles. _Parasites._ We have before us a long list of parasites[26] which infest the Cockroach. There is a conferva, an amœba, several infusoria, nematoid worms (one of which migrates to and fro between the rat and the Cockroach), a mite, as well as hymenopterous and coleopterous Insects. The Cockroach has a still longer array of foes, which includes monkeys, hedgehogs, pole-cats, cats, rats, birds, chamæleons, frogs, and wasps, but no single friend, unless those are reckoned as friends which are the foes of its foes. [26] See Appendix. _Names in common use._