36 THE STRUGGLE FOR EXISTENCE 



seem, however, as if even this chance were small 

 and as if still further protection were needed. 

 And one further protection seems to be afforded in 

 some species in a peculiarity of their life history. 

 Apparently the species of Basilarchia are, at least 

 in New England, normally single brooded ; but in 

 not infrequent cases, doubtless more frequent in 

 southern than in northern parts, a second or 

 supplementary brood is formed in one season ; as 

 the butterfly lays eggs for some time, and all the 

 females are not born at once, the earliest progeny 

 of the earliest females may not infrequently be 

 able to mature in the same season in time for the 

 production of a second brood. This would seem to 

 be a provision on the part of nature to give the 

 species a better chance. That they need it is 

 perhaps evidenced by the fact that the black- veined 

 orange species, which are almost universally more 

 numerous in individuals than the others, have, in 

 regions where one brood is the normal condition 

 of their fellows, always two broods. 



But this is not the only advantage the black- 

 veined orange species have, so that we cannot 

 fairly ascribe their greater numbers to this alone. 

 Their very colors are an advantage to them, for in 

 them they mimic species of another group, the 



