Ciiap. X. 
SEXUAL SELECTION. 
341 
CHAPTER X. 
Secondary Sexual Characters of Insects. 
Diversified structures possessed by the males for seizing the females 
— Differences between the sexes, of which the meaning is not 
understood — Difference in size between the sexes — Thysanura 
- — Diptera — Hemiptera — Homoptera, musical powers possessed 
by the males alone — Or thoptera, musical instruments of the 
males, much diversified in structure; pugnacity; colours — 
JXeuroptera, sexual differences in colour — Hymenoptera, pugnacity 
and colours — Coleoptera, colours ; furnished with great horns, 
apparently as an ornament ; battles ; stridulating organs generally 
common to both sexes. 
lx the immense class of insects the sexes sometimes 
differ in their organs for locomotion, and often in 
their sense-organs, as in the pectinated and beauti- 
fully plumose antennae of the males of many species. 
In one of the Ephemerae, namely Ohlceon, the male 
has great pillared eyes, of which the female is entirely 
destitute . 1 * * The ocelli are absent in the females of 
certain other insects, as in the Mutillidae, which are 
likewise destitute of wings. But we are chiefly con- 
cerned with structures by which one male is enabled to 
conquer another, either in battle or courtship, through 
his strength, pugnacity, ornaments, or music. The 
innumerable contrivances, therefore, by which the male 
is able to seize the female, may be briefly passed over. 
Besides the complex structures at the apex of the abdo- 
men, which ought perhaps to be ranked as primary 
1 Sir J. Lubbock, ‘ Transact. Linnean Soc/ vol. xxv. 1866, p. 484. 
'With respect to the Mutillidse see Westwood, 4 Modern Class, of Insects/ 
vol. ii. p. 213. 
