STATES OF INSECTS. 309 



iv. In many cases, the structure of particular parts and 

 organs of the body differs in the sexes. As the facts con- 

 nected with this part of our present subject are extremely 

 numerous and various, it will be convenient to subdivide 

 it, and consider the sexual characters that distinguish — 

 the Head, Trunk, and Abdomen of insects, and their se- 

 veral appendages. 



1. The Head. This part in some females is consider- 

 ably larger than it is in the male. This is the case with 

 the ants, and several other Hymenoptera ,• while in some 

 Andrence, as A. Jicemorrhoidalis, and Staphylinida?, as 

 St. olens, that of the male is the largest. But in none is 

 the difference more conspicuous than in the stag-beetle 

 {JLucanus); in which genus the male not only exceeds the 

 female in the length of his mandibles, but also greatly 

 in the size and dimensions of his head. In the Apion 

 genus, the rostrum of the female is generally longer and 

 slenderer than that of her mate; and in Brentus, the 

 rostrum of one sex (probably the male) is long and fili- 

 form, while in the other it is thick and short. This is 

 particularly visible in B. dispar and maxillosus a , &c. 



One of the most striking distinctions of the males in 

 this part of their body, are those threatening horns, usu- 

 ally hollow, with which the heads of many of the male 

 lamellicorn insects and some others are armed, and which 

 give them some resemblance to many of the larger qua- 

 drupeds. Many are unicorns, and have their head armed 

 with only a single horn ; which in some, as in Oryctes 

 Illig., Dynastcs Endymion b , &c. is very short ; in others, 



> Oliv. no. 84. Brentus, t. If. \.b. c. I. li.f. 17. a. b. 

 b Oliv. no. o. ScarabcBus, t. xviii./, 169. 



