32 



NATURE 



[Nov. 12, 1874 



Edward Hermon, Esq., M. p. for Prestcn ^i i o 



Capl. J. Hcrschel, F.R.S., &c I I o 



The Parish of Hoole 5 5° 



The Right Hon. Lord Houghton, F.R.S., &c I i O 



Wilham Huggins, Esq.,D.C.L., LL.D., F.R.S., Fo- 



reigi: .Secretary of the Royal Astronomical Society i i o 



.Sir J. Kay-Shuttleworth, Bart. i i o 



William Lassell, Esq., F.R.S., &c I I o 



Lord Lindsay, M. P., S:c i i o 



T- Norman Locl;yer. Esq., F. R.S., tic I I o 



The Riglit Rev. the Bishop of Manchester I i o 



Mrs. Charles Orme I i o 



Mrs. G. M. Patmore I i o 



William Pollard, Esq I i o 



The Rev. Charles Pntchard, M.A., F.R.S., Savilian 



Professor of Astronomy in the University of Oxford i i o 



Richard A. Proctor, Esq., B.A., &e. &c i i o 



A. Cowper Ranyard, Esq., M.A., Secretary to the 



Royal Astronomical Society I i o 



TheEarlof Rosse, F.R.S., &c. &c I i o 



Henry J. S. Smith, Esq., M.A., F R.S., Savilian 



Professor of Geometry in the University of Oxford i i o 



F. Styles, Esq 1 i o 



General Treasurer — Prof. Adams, the Observatory, 

 Cambridge. 



The Rev. R. Brickel, the Rectory, Hoole, Preston, 

 Lancashire ; Prof. Grant, the Observatory, Glasgow ; 

 Mrs. G. M. Patmore, 81, Avenue Road, N.W. ; and A. 

 Cowper Ranyard, I- sq., 25, Old Square, Lincoln's Inn, 

 W.C, have kindly promised to receive and acknowledge 

 subscriptions. 



FERTILISA TION OF FLO WERS B Y INSECTS * 



vn. 



Biitierflies the )nost frequent visitors of Alpine flowers. 



IN the following article I wish to recommend for 

 further inquiry a subject of peculiar interest which, 

 in the environs of the Ortler, in Tyrol, forced itself on my 

 attention last summer, but which, during my short stay 

 in the Alps (5—25 J'j'y)) I li^d i^ot \ya-\^ to investigate so 

 thoroughly as it deserves. Whilst occupied, along 

 with my son, in observing the Alpine flowers and their 

 fertilisation by insects, we were struck with the very small 

 number of Apidae met with in higher Alpine (subnival) 

 localities, and with the predominant part which butterflies 

 play in this region in relation to the fertilisation of flowers. 

 In the environs of "PizUmbrail" and" Quarta Cantoniera," 

 3,000 — 2,400 metres above the sea-level, we observed only 

 four humble bees, and not a single individual of any other 

 genus of Apidce during a sojourn of five days, and in spite 

 of very line weather, whilst numerous Coleoptera (Dasytes, 

 Anthobium, Anthophagus), many Diptera (especially 

 Muscidre and Syrphida;), and very numerous specimens 

 of some species of Lepidoptera were found in the flowers 

 of this region.^ Between 2,400 and 2,100 metres (de^ 

 scending towards Bormio and in the environs of Fran- 

 zenshoh and Trafoi) the number and variety of Apida?, 

 other Hymenoptera, Coleoptera, and Diptera proved to 

 be much greater ; but, at the same time, the number and 

 variety of Lepidoptera increased to such a degree that 

 this order of insects was in unmistakable preponderance 

 also in this region.. I In the plain, near Lippstadt, on the 

 contrary, and in the lower mountainous region of Sauer- 

 land, Thuringia, and Fichtelgebirge, Diptera, but more 

 especially ApidK, are the most frequent visitors of flowers, 



I from vol. X. p. 130. 



+ Rhopalocera : Picris callidice Esp., Lycaena orbitnlus Prunn., L, 

 sciniargus Rott., Melitiva vterope Prunn., M. Jtarthenie Bkh, var. varia. 

 I\I.D., Ar^ynnis fiaUs'Wy , Erebla tyndarits Esp. Geometric; Psodos 

 alptnata Scop., Pv^ntcEita fusca Thbg. Crambina : Hercyna schrankiana 

 Hoch. (Hohsericalls H.), H. /•Iirygialis H., H. rufestratis H., Cramius 

 liict'/rrrllus H.-accordmg to Dr. Spsyer's determination. 



t We fjund here Rhopalocera 33, Sphingidse 4, Bombyces 5, Nocture 3, 

 Geometrae 3, Crambina 6, Tineina 2, Pterophorina i, altogether 57 species of 

 Lepidoptera visiting flowers. 



although in the latter region a considerable increase in the 

 proportion of Lepidoptera may be remarked. 



Consulting our highest authority on the geographical 

 distribution of butterflies in Germany and Switzerland, Dr. 

 Speyer, of Rhoden, I heard that the fact alluded to would 

 be in direct opposition to the general distribution of the 

 species of Lepidoptera in altitude, the number continu- 

 ally decreasing from the lower mountainous to the higher 

 Alpine (subnival) region ; only the plain, as it seems, 

 being somewhat poorer. This contradiction, however, 

 may be, and, as I am convinced, from my observations, 

 is, only an apparent one ; for, notwithstanding the smaller 

 number of species, the absolute frequency of Lepidop- 

 terous individuals, and perhaps also of species, is con- 

 siderably greater in favourable Alpine localities than in 

 equally large tracts of the lower mountains and of the 

 plain, firstly in consequence of the smaller number of 

 Alpine species distributed over a very restricted area ; 

 and secondly, because many of these species are repre- 

 sented in their restricted localities by a surprising number 

 of individuals. Dr. Speyer himself writes me : " I have 

 also myself been frequently struck with the great number, 

 not only of individuals, but also of species, met with in 

 favourable Alpine localities." Moreover, the relative fre- 

 quency of butterflies, which alone :s concerned in esti- 

 mating their importance in the fertilisation of flowers, seems 

 to be still greater than their absolute frequency in the 

 higher Alpine (subnival) region ; insects of other orders, 

 with exception of the Diptera, apparently decreasing in a 

 still larger ratio towards the snow-line. In order to appre- 

 ciate adequately the differences of frequency alluded to 

 and the share taken by butterflies in fertilising flowers in 

 different regions, it would be necessary to ascertain the 

 exact number of individuals of Lepidoptera and of other 

 insects that visit certain flowers of the different regions in 

 a given time. Llnfortunately I have neglected such obser- 

 vations, and can only give some statistical data as to the 

 number of species of Lepidoptera and other insects ob- 

 served by myself to visit flowers in difterent regions. 

 These data can afford but an approximate idea of the 

 above differences, but they will, I hope, sufficiently show 

 that these differences are by no means a product of my 

 imagination, but a matter of fact, and that in Alpine regions 

 Lepidoptera are really of considerably greater importance 

 in relation to the fertilisation of flowers than in the plains. 



There are some few species of flowers which I have had 

 the opportunity of observing as to their visitors both in the 

 plain or in the lower mountainous and in the Alpine region ; 

 these, of course, will be the most useful for comparison. 

 For the sake of a more easy survey of the statistical notes 

 I shall make use of the following abbreviations : « = in 

 the plain, near Lippstadt ; 1^ = in the lower mountainous 

 region of Sauerland, Thuringia, Fichtelgebirge ; c = in 

 the Alpine region, near Trafoi, Franzenshoh, Quarta 

 Cantoniera ; Ap. = Apidse ; Lep. = Lepidoptera ; O.l. = 

 other insects. 



The following is a list of the visitors to different plants, 

 so far as I have observed. 



I. Helianthemuvi vidgare :— 



b. Ap. 5, Lep. t, O.L 16 species; Ap. 23, Lep.* 5, O.I. 72'per cent. 



2, Lotus corniculatus : — 



a. Ap. 19, Lep. 5, O.I. 2 species 



Ap. 73, Lep. 19, O.L 

 .. 6s, „ 27. ., 



3. Prunella vulgaris : — 



a. Ap. 8, Lep. 4, O. L o species ; Ap. 6C, Lep. 33, O L o per 



b. „ 4, ,, 2, ,, o ,, ,, 06, ,, i^, ,, o ,, 

 '■■ .1 ', .. 4. .. I .. .. 17. ., 67, „ 17 „ 



* It should be noticed that as the flowers of HetianthemKm 

 do not secrete honey, Lepidoptera must either obtain a little of the 

 the flowers by boring, or are altogether deceived. 



t In the Alpine region my observations have been made on the vat 

 florum. 



ju.cesof 

 '. grandi- 



