338 A!cari infestiiig Buttejjlies, 



between the legs, at the base of the wings, and at the junctures 

 of the thorax with the head and with the abdomen, both above 

 and beneath. The insects on which I have chiefly observed 

 it are, Hippdrchia Galathea {Jig, 74. h) and Jamr«, Polyom- 

 matus rcaru5 (a), and Adonis, Anthrocera filipendulae, and. 



in one instance, C^nthifl' cardui, but particularly Hipparchia 

 Galathea. The common white butterflies (P6nti« brassicae 

 and rapae) appear to be free from this pest ; at least, I have not 

 been able to detect a single ^'carus on any one of the number- 

 less individuals of those species which I have examined for that 

 express purpose. It is no uncommon occurrence, to see the 

 small blue butterflies (Polyommatus Tcarus and Adonis) flying 

 about, as it should seem, with perfect ease and indifference, 

 and apparently in full enjoyment of life, while some half 

 dozen of these ^'cari are adhering to them, and deriving 

 sustenance from the juices of their slender bodies. If %ioe were 

 to be encumbered with vermin of a proportional magnitude, 

 it would be like having a number of creatures as large, per- 

 haps, as moderately sized lobsters sticking to our flesh, and 

 preying upon our vitals. Perhaps some of your correspond- 

 ents may be able to throw more light on the history of this 

 little insect. It would form, I may suggest, a fit subject for 

 the exercise of our friend Mr. Westwood's microscopic acu- 

 men. How, for example, does the ^'carus first gain a lodge- 

 ment on the Lepidoptera it infests ? And how is the race 

 continued after the butterflies die in the autumn ? Is the 

 insect most generally found to abound in chalk districts ? &c. 

 &c. I may observe, that, in the autumn, the v4'cari had nearly 

 disappeared from the butterflies, long before the latter had 

 ceased to fly abroad. 



It may be proper to add, that, of the specimens of ^'cari 

 which I send herewith, some have been gummed on paper, in 

 order the better to exhibit them, and others have been fixed 

 by the same means in their natural position, just as they 

 adhered to the butterflies on which they were found : in the 



