6o A YEAR OF COSTA RICAN NATURAL HISTORY 



females are also found in which the orange area of the abdo- 

 men is faintly or deeply clouded or almost black. Com- 

 bining all this evidence, the conclusion seems justified that, 

 in this species at least, the "black" females are merely older 

 stages of those which formerly were "orange." There is 

 thus a marked color change accompanying age in the female 

 sex of this species, but not in the male. 



Even greater color changes of this character may be found 

 in both sexes of another species far more abundant about 

 Cartago — Anisagrion allopterum. The individuals which 

 have just transformed from the larval stage and expanded 

 their wings, so that they are able to fly weakly, have the 

 head and thorax of a pale dull brown ("light pinkish cin- 

 namon") and the abdomen of a pale yellowish with a dark 

 brown or black cross ring at the hind end of most of its 

 segments. Eventually, when some pruinosity is visible on 

 limited parts of the body, the head has become black above, 

 between the eyes, with four adjacent blue spots, the thorax 

 is of a greenish-blue with a middle black stripe and a black 

 shoulder stripe each side, and the abdomen is black above 

 except for a fine pale bluish ring at the fore end of each of the 

 second to the seventh segments. 



It is evident, therefore, that a very great difference exists 

 between the colors of the recently metamorphosed individ- 

 uals and those which are partly pruinose. As we found 

 individuals representing many intermediate conditions, fly- 

 ing in the same localities, it seems justifiable to conclude 

 that the difference represents a change accompanying ad- 

 vancing age. This conclusion is strengthened by the fact 

 that those with pale colors possess a weaker and softer chiti- 

 nous covering on their bodies, while the predominantly 

 black ones have a much firmer and harder exoskeleton. 



The color changes which take place in the different re- 

 gions of the body of this Anisagrion appear to be, to some 



