OF INSECTS. 303 



there is no trace of them, except in the costal alone, 

 which loses itself in a scarcely perceptible stigma/'* 



The value of the generic characters afforded by 

 the modifications which the figure of the cells under- 

 goes, may he inferred from the fact stated by M. 

 Jurine, that he could, in most cases, determine the 

 genus of a hymenopterous insect from the inspec- 

 tion of the wings alone. 



As among the Hemiptera, the inferior wings are 

 more or less closely united to the superior when in 

 action, but this is effected by a different kind of 

 mechanism. Along the anterior edge of the secon- 

 dary wings is placed a series of very fine hooks, 

 (hamulij) which attach themselves to the hinder 

 margin of the primary pair, and a continuous sur- 

 face of some extent is thus presented to the air. 



From the preceding details it may be inferred 

 that the Hymenoptera possess great powers of flight. 

 It is in fact one of the orders in which that power 

 has reached its maximum; all the necessary con- 

 ditions being found united. The great distances to 

 which bees fly in search of honey, often against a 

 strong wind, are well known ; and even when they 

 are loaded with pollen, or other substances with 

 ** treasures sucked from buds and bells" the rapidity 

 of their aerial movements appears in no degree re- 

 tarded. 



The humming noise which many of them emit is 

 not produced by any organs specially formed for that 

 purpose, as among the Hemiptera and Orthoptera, 

 * Intro, a PEntom. I. 368. 



