92 THE CAUSES WHICH PROPAGATE 



From this variation in wing outline^ too, arise eccentricities 

 of flight in males at the pairing time. Thus certain beaux of 

 the Liparidae and BombycidsBj with comb-like antennae and 

 falcate wings ap2:)roximating (Fig. 2), zigzag vertically in air, 

 and hunt backwards and forwards, searching for the female, 

 who, apterous, or with wings paler in livery, displays on her 

 cocoon, the herbage, or a tree trunk. These when diurnal in 

 habit pair at noon, on the advent of a cloud-shadow or summer 

 mist."^ Many butterflies similarly search for a partner, and 

 then pair at noontide when the sky is overcast, love here acknow- 

 ledging a kindred stimulus to fear and anger. 



Vertical figure dancers, when examined, will be found to 

 have a stereotyped wing outline, lanceolate^ or lancet-shaped, 

 with the maximum breadth nearest the tip, which sustains their 

 balance (Fig. 5). They are widely distributed in the orders, 

 with exception of bugs and beetles. As regards butterflies, Mr. 

 P. Gosse tells us the South American Hellcouia Charitonia before 

 sundown aggregates in a dance after the fashion of gnats, and 

 the individuals then sleep the night in groups of half-a-dozen on 

 the leaves of the creepers, f The heteroceral dance is attractive, 

 and promotes sexual intercourse in the case of the common 

 Ghost Moth, whose silvery-white males swing pendulum-like 

 over the grass of low damp meadows, until some yellow female 

 careering wildly along collides with one, who immediately 

 follows her, and they pair. J The orange-coloured males of 

 the Golden Swift likewise dance under lonely hedgerows, and in 

 more accurate curves, although the female of their darker con- 

 gener the Northern Swift ascends at dusk a bracken frond on 

 Scottish moors to allure its fleet-winged mates that dart around. 

 In similar fashion the sylvan twilight is enlivened during the 

 freshness of early summer by the brisk swinging movement of 

 glossy-winged societies of the Long-horned Adelse, which when 

 silence falls and the shades of dusk creep on, yield in turn to the 

 similar antics of the sickly yellow Nemphorse. 



The males of some Neuroptera dance and collect, and when 

 joined by their attracted females they pair. Over low alluvial 



* Trans. Ent. Soc. do la France. f Glosseia Charitonia. 



X Ent. Mon. Mag., V. VIII., p. 63. 



