Insects. G81 



[These creatures are evidently Acari, and are so minute as scarcely to be observa- 

 ble without the aid of a lens : the colour is now a uniform pale dull yellow ; the ros- 

 trum is short and very acutely pointed, it has an evident longitudinal groove ; the che- 

 licerae are very stout, incurved, acutely pointed, and equal to the rostrum in length ; 

 the legs are eight in number, and widely separated at their base, all of them slender, 

 the 1st and 2nd pairs more so than the others, and very much longer. Nothing is 

 more common than for insects to be infested with minute Acari : an anecdote on this 

 subject has long been an article of profound faith among entomologists. A brother of 

 the net was standing up under a tree, to avoid the pelting of a passing shower. A huge 

 humble bee flew heavily towards him, and alighted on an ant-hill at his feet. The 

 ants being driven in by stress of weather, did not observe the visitor, so he set to and 

 tore up the surface of the hill in fine style ; out came the ants in a desperate passion, 

 and soon assailed the leviathan that had so unceremoniously injured their habitation. 

 The entomologist went down on his hands and knees to see the issue, when to his sur- 

 prise he found that the bee was infested by a multitude of Acari, and that the ants 

 were picking them off and carrying them away. This task was speedily accomplish- 

 ed; the bee rose on humming wing, and went about his usual avocations; and the 

 ants again retired within their nest. — Edward Newman]. 



Note on Pontia Metra. I am disposed to consider this insect as merely a variety 

 of P. Rapae, and not a distinct species, which some entomologists have pronounced it 

 to be. From the circumstance of its earlier appearance than P. Rapae ; from its being 

 in general smaller, and apparently more delicate; and from its not occurring later in 

 the season, when that insect is so abundant; I, for some time, believed it to be speci- 

 fically distinct : last autumn, however, I took numerous caterpillars of P. Rapae, evi- 

 dently belonging to the same brood, and exactly corresponding in appearance one with 

 another in every respect, which shortly after underwent their transformation in the 

 breeding-cage. The perfect insects have now emerged, and from these same caterpil- 

 lars have been produced every variety of Rapae and Metra respectively; some exactly 

 corresponding with the description referrible to each insect, and others presenting an 

 appearance between the two : some have the spot on the upper disk of the anterior 

 wing entirely wanting, others with it obsolete, others with it very distinct, and the tip 

 more or less so ; others again are sprinkled all over the largest portion of the upper 

 side of the wings with dark points. These dark points, which occasion a dusky ap- 

 pearance, when subjected to the microscope, are found to be scales, similar to those 

 which compose the spot on the disk and the tip of the anterior wing ; and are in shape 

 much longer and narrower, and of a deeper and richer colour than the ordinary scales. 

 I have not found any variation in form and colour between these 

 darker scales taken from the wings of specimens of P. Rapae, and 

 those from individuals usually referrible to P. Metra ; but some 

 of the commoner scales, taken from the wings of certain speci- 

 mens, present a very marked difference. I am not, however, 

 aware, whether a variation in the form of the scales on the but- 

 terfly's wing has ever been adopted, or is to be considered admis- 

 sible, as an additional criterion, whereby to judge generally of V >7|)\V 

 the specific distinction between insects closely approximating- to 



i ., r i • i .i. i ■> ■. ,. Scale from the wing of 



each other in appearance, of which the larva has not been disco- p. Metr*? magnified. 

 vered. From the wings of some, having the spot on the disk very distinct, I have ta- 

 ken numerous scales shaped as in the margin; from examples which would indubitably 



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