HYMENOPTERA. TEREBRANTIA. 183 



Here, again, is a structure which leads to inquiry, and 

 our experience of the large-thighed beetles naturally 

 leads us to expect great Fig 51 



power in leaping in 

 these little flies. But 

 what is the fact ? That 

 many of them possess 

 no such power, and that 

 we find no reason what- 

 ever for this extra- 

 ordinary development. 



The lesson, therefore, 



' Chalcis Clavipes. 



which we have learned 



from the little Chaicis, is not that we may safely presume 

 upon our experience to jump at conclusions, hut that when 

 we feel most certain beforehand of how our natural history 

 facts ought to turn out, we had need to be most careful 

 to ascertain whether they may not prove exactly contrary. 

 Some of these little creatures are parasitic upon other 

 parasites, whose presence they discover whether on the 

 exposed body of a naked insect or in the grub enclosed 

 within a gall ; many rejr upon the gall grub itself. One 

 of these, Callimome flavipes, found in the round hard 

 oak-gall, is described by its discoverer, Mr. Parfitt, in 

 terms which present an image to the mind only less 

 gorgeous than Blake's vision of the green-mailed ghost 

 of a flea, holding its golden cup of blood. " Wings 

 splendidly iridescent; head, thorax, and abdomen beneath 

 of the most magnificent shining green ; the basal and 

 two next segments of the abdomen very highly polished, 

 and reflecting a steel-blue in certain lights; eyes 

 brown, &c. The length of this glorious atom is about 

 a quarter of an inch." 



