INSECTS AND PLANTS 59 



expansion of three inches. The under side of the abdomen 

 is a dull orange colour, and, in the male, four or five of the 

 segments on the upper side are of the same colour. The 

 smaller form is about two-thirds the size of the larger, and 

 it appears and disappears some ten days later in the season 

 than its larger brethren. 



It may reasonably be inferred that, early in its existence, 

 the periodical cicada of America was represented by a 

 single brood ; in that event, it would have appeared every- 

 where over its range at the same time. In the long course 

 of ages this original brood would have become broken up, 

 with consequent divergence of the dates of appearance, so 

 that, at the present time, practically every year has its 

 brood or broods, upwards of twenty having been differen- 

 tiated, studied, and recorded, with the result that the Ameri- 

 can Bureau of Entomology can foretell when and where a 

 brood may be expected to appear. 



The periodical cicada belongs to the order Rkynchota 

 and the sub-order Homoptera, therefore it is closely related 

 to the scale insects and aphides ; they are the largest and 

 most striking insects of their sub-order, and, because they 

 possess the power of " song," have been invested with great 

 popular interest since the time of Homer. Black in colour, 

 for the most part, it has beautiful orange-red eyes and 

 limbs, and the principal veins of its four, almost transparent, 

 wings are similarly coloured. 



Contrary to our usual practice, we will give some atten- 

 tion to the structure of two of the insect's organs, viz., the 

 organ of song and the ovipositor, for they are of special 

 interest. With regard to the organ of song possessed by 

 this insect, it is curious and interesting to note that the 

 fullest and most accurate description was given by Reaumur 

 as long ago as 1740, in his Histoire des Insectes, and 

 although the organ has been studied by many later entomo- 

 logists, little has been discovered that escaped the notice 

 of the celebrated French naturalist. 



