Entomological Society. 3891 



the roots of an elm, I turned up a large lump of baked clay. On breaking it, I found 

 no fewer than sixteen pupae of Taeniocampa instabilis imbedded in it : the shells were 

 quite brittle, and on opening them I fouud the insect perfectly developed, but dead. 

 Another cause which tends to make insects scarce or uncertain in their appearance, is, 

 of course, the Ichneumon, that foe to the entomologist. The havoc committed by them 

 would appear incredible to those who have not witnessed their destructive powers as I 

 have, while digging for pupae. Take, for example, Lithosia rubricollis. At Guiting 

 I found the pupae of this insect by hundreds. It is no exaggeration to say that three- 

 fifths at least of these had been destroyed by Ichneumons. Their empty pupa-cases, 

 with the circular opening always made by the Ichneumon, lay scattered about by do- 

 zens ; and I have repeatedly liberated the parasite itself in turning up the sod. 



" It may be asked — ' How do you know the species of those pupae which are as yet 

 undisclosed ?' To this I would answer, chiefly by experience. As a general princi- 

 ple, it is not difficult to decide to what family a pupa belongs. A Bombyx may some- 

 times be known at once by its form, which nevertheless varies considerably. More- 

 over, all Bombyces form a web or cocoon, at least all those with which I am acquainted 

 in the pupa state. This, however, is by no means a decisive criterion, as some Noctuae 

 (Acronycta) and Geometrae (Tephrosia) do the same. Still, I think a Bombyx maybe 

 known with tolerable certainty, if attention be paid to the following peculiarities: — 1. 

 A web or cocoon. 2. The bulky form of the pupa, which is almost invariably either of 

 a nearly uniform thickness throughout, and round, or else stout to the middle and ra- 

 pidly tapering to a point. 3. The form of the antennae (which is an excellent criterion) 

 and the invariable shortness of the wing-cases : to this I call particular attention. The 

 genus Lithosia, of which, however, I tnow only two species in the pupa state, is an 

 exception to some of these rules. Examples of the rounded form will occur to every 

 one, as Orgyia potatoria, Cerura bifida, C. furcula, &c. As an example of the taper- 

 ing form I may mention Orgyia Coryli. Some of the genera, also, among the Bom- 

 byces may readily be distinguished by the form of the pupae ; I may mention in parti- 

 cular Notodonta. I think I could instantly detect a pupa of that genus from its form. 

 I have either reared or found in pupa, Notodonta Camelina, Chaonia, Dictaea, Dic- 

 taeoides, Dodonaea, Dromedarius trepida and Ziczac. In all these (with the exception 

 of Camelina, which slightly differs) the pupa is round, of a nearly uniform thickness, 

 rounded at the anal extremity, and ribbed. 



" The genus Lithosia is quite different. The pupae which I have had (L. rubricol- 

 lis and aureola) are short and stout, expanding somewhat in the middle, and tapering 

 slightly towards each end. 



" The Geometrae are easily distinguished by their size and slender shape, except 

 the genera Biston, Phigalia, Nyssia, and part of Ennomos. They are, moreover, the 

 most active pupa?, except perhaps some species of the genus Acronycta. 



" It seems to me quite impossible to assert, wiih any degree of certainty, as to what 

 subfamily or genus of Noctuae or Geometrae a pupa belongs to, or to assign any data by 

 which to decide, except, perhaps, experience and observation ; and even then, owing to 

 the great resemblance of many species to each other, one is constantly liable to error. 

 The tree at which a pupa is found will sometimes assist, as showing the food ; but 

 even this is uncertain, as I have found the pupae of insects, whose larvae are supposed 

 to feed on only one particular tree, at many others. I believe, for example, that the 

 larva of Acronycta Ligustri is said to feed on privet ; I never took it there, but have 

 found the pupa under moss on willow, beech, ash, aud oak.'' 



