MORPHOLOGICAL EFFECTS OF CROWDING 319 



that the collection in bands produces a coloration which increases 

 the internal heat by increased absorption of the sun's rays, and that 

 this in turn increases activity of the animals and is responsible, at 

 least in part, for a greater tendency to wander. Apparently, the 

 behavior and the coloration may be found to be inextricably inter- 

 mixed with various other physiological processes and their morpho- 

 logical expressions, which have as yet escaped analysis. 



The transition from a wingless band of hoppers to a winged swarm 

 is gradual. The first winged forms to appear continue to move as 

 hoppers with the wingless nymphs. Later, when more are molting 

 to the adult form, the behavior of the band is modified; they rest 

 much and are easily disturbed. After some days, isolated winged 

 forms take off, fly in a circle, and again settle. When they pass 

 over other winged individuals, these too may take to the air, per- 

 haps as a response to air vibrations, as suggested by Vayssiere 

 (192 1), since blinded locusts will respond, although those with eyes 

 intact fail to do so if they are inclosed in glass (De Lepiney, 1928). 



Faure (1923) gives almost the same account for the brown locust, 

 Locustana pardalina, of South Africa. He reports that the bands of 

 hoppers may be composed of three or four distinct nymphal stages, 

 although they are more usually of the same stage. The members of 

 a band do not all molt to form flying insects on the same day, but 

 the winged males and females remain with the main band, probably 

 until there are enough winged individuals to make a separate swarm. 

 These precocious flyers camp with the main band at night even 

 though they have ranged widely through the day. 



Very large flying swarms travel for hundreds of miles. Small 

 ones tend to remain near where they became winged. The distance 

 covered is greater during the first few weeks of adult life. Later, as 

 the females become heavy with eggs, the swarm tends to break up 

 into sections. At night these flying swarms collect in clusters which 

 are not so dense as those of the hopper bands. In South Africa 

 brown locust swarms may fly on moonlit nights, particularly if 

 harassed by birds. It is noteworthy that compact swarms leave 

 large deposits of eggs behind. 



Ordinarily, these locusts which Faure describes feed upon sweet 



