60 THE CAUSES WHICH PROPAGATE 



love and rivalry, in the dances, music, and migration of insects, 

 will then appear that, while music and display present pai-allel 

 characters chiefly exhibiting love and rivalry and promoting the 

 union of the sexes, migration, aerial and terrestrial, very generally 

 takes origin in the same phenomena, and arises from the same 

 stimuli. 



The principal phenomena which mark the reproductive period 

 of insects as we have observed are dances and music. We have 

 shown that the battle of males for the female that burns so fiercely 

 in higher organisations, which gave antlers to the stag, horns to 

 the bull, spurs to the cock, and incisive weapons to the fish, 

 smoulders yet more intensely in mandibulate insects of the 

 Orthoptera, Coleoptera, Hymenoptera, and Neuroptera, many of 

 whom bite and devour one another — a temper that extends to 

 the females of many spiders ; but, generally speaking, in a state 

 of nature this influence is more gentle, especially in the case of 

 suctorial kinds, as Lepidoptera, Diptera, Hemiptera, Homoptera, 

 and many Neuroptera, which are, with the exception of the 

 Bugs, where the cibarial organ is no longer for licking, but 

 pricking, unarmed. And thus we find the fundamental stimuli 

 of anger and rivalry not confined to battles of which the sex is 

 the immediate object, but taking general expression in pheno- 

 mena of dances and music, which are inspired by an emotion 

 in cases common to the sexes. Thus we shall find that, 

 while some males at a certain season form a dance and are then 

 joined by the females, others pass their third stage in these 

 performances, and others merely an early-winged period of the 

 perfect state ; while some, again, collect and pursue the female, 

 or the female, on the contrary, collects the males. 



Again, the feathered tribes, which in many cases exhibit 

 similar sports at the pairing season, have a twofold method of 

 communication, namely, a vocal music produced by the larynx, 

 generally a mere jealous chirping, but which among the males 

 at the breeding season acquires most exquisite modulation in call- 

 notes like those of the nightingale and mocking-bird; also a 

 faculty resident in the male of emitting drumming sounds to 

 attract his - female by means of the wing or tail, which are 

 generally given out in air, but sometimes produced by solid per- 

 cussion, and have been termed instrumental music. Both 



