From John William Douglas 20 February 1868
British Hemiptera. Heteroptera1
1 The sexes Different in colour or ornamentation.
| 1. | Female paler than the male | ||||
| Ex. Jalla dumosa, Lin. (See Hahn, Wanz. i, figs. 54 ♂, &55 ♀.) | |||||
| Systellonotus triguttatus, Lin. (See Brit. Hem. Pl. XII, fig. 2 & 2♀.)2 | |||||
| In this latter case the ♀ is decidedly less conspicuous than the ♂. the former being without elytra and paler brown body, the latter with conspicuous marking on the elytra. (see also No 2 Head Difft. form) | |||||
| Apocremnus ambiguus, Fall. | } | male black or dark:female red or reddish. | |||
| " obscurus, Kirscht. | |||||
| Sthenarus Roseri, H Schf. | |||||
| Capsus capillaris, Fab. | |||||
| { | male black;pronotum3 of ♀ reddish. | ||||
| Rhopatolomus ater, Lin.4 | |||||
| { | Zygonotus pselaphiformis, Westn. | ||||
| in the ♂, the elytra brown with markings | |||||
| See also difference of form | in the ♀ light brown without markings | ||||
| 2 | Female darker than the male— | ||||
| Sphyrops ambulans, Fall. | } | male brownish, ♀black. | |||
| Byrsoptera Caricis, Fall. | |||||
| Myrmedobia coleoptrata, Fall. | |||||
| 3 | Female varied | ||||
| Zygonotus elegantulus Baerens.5 | male elytra brown with markings; ♀ apterous pronotum red, body black | ||||
As a rule the sexes do not differ much in colour, the above are the chief exceptions.
I have not the material at hand to say anything special respecting the colour of exotics, but as far as I knw variation of it in the sexes is exceptional
2. The sexes different in size or form
As a general if not universal rule the ♀ is generally larger and more robust than the ♂; often, especially in Capsina and Anthocorina,6 the males have longer elytra than the females making the insects look larger than they are. In the genera Orthocephalus, Fieb., Bothynotus, Fieb. and in Sphyrops ambulans, Fall. Byrsoptera caricis, Fall., Myrmedobia coleoptrata, Fall. the ♀ looks remarkably different from the ♂, the body being very short and wide; and the elytra shorter still; in the last named the elytra fit close to the rounded abdomen like those of a beetle, Alexia pelifera. In Zygonotus elegantulus, Baerens., the ♂ has long elytra, brown with markings, the ♀ is apterous, pronotum bright red, abdomen short wide and black (See Brit. Hem. pl. xvi, fig. 1, 2, & 3, ♂ & ♀.7
3. Difference of structure of parts.
In addition to the difference in the elytra above mentioned may be noted
| 1 | Form of head | ||||
| Genus Globiceps—larger and more globose | |||||
| 2 | Form of antennæ.—x2d joint thickened in ♀— | ||||
| Genus Globiceps—especially in G. dispar, Boh. see Ent Mag.iv, | |||||
| pl. 1 figs 4, ♂ & ♀. | |||||
| Genus Heterocordylus—especially H. unicolor. | |||||
| xx 2nd joint thickened in ♂— | |||||
| Genus Apocremnus, Fieb. | |||||
| Ex. A. ambiguus, Fall. | |||||
| " | A. obscurus, Kirschb. | ||||
| xxx 2nd joint curved and remarkably produced at the apex, in ♂—in ♀ simple | |||||
| Ex. Harpocera thoracica, Fall. (Brit. Hem. pl. 15, fig 3a)8 | |||||
| 3 | Form of tarsi.— In the genus Corixa, the monomerous tarsi of the fore-legs in the ♂ are remarkably larger than in the ♀, and though in all species cultrate, yet in each is a modification of size and shape. (See Fiebers’ ‘Species Corisarum’).9 | ||||
Musical powers— The faculty of stridulation occurs (as far as I know) only in the Homoptera and is confined to the males of the genus Cicada. There is but one species known in Britain— C. montana, Scop.,10 and the evidence of its musical powers is contradictory and therefore unsatisfactory. Of the foreign species, in this respect, I know nothing except by books. Nor, also, can I say, whether the curious appendages seen in exotic Homoptera are sexual or not, or are modified in the sexes. Nothing, as far as I know, has been observed of the courtship of the sexes in the Hemiptera.
The foregoing remarks as to difference of colour in the Heteroptera, speaking generally, will apply, I think to foreign species—though I doubt not there are as in our own Fauna, special exceptions, for which there seems to be no rule.
In the Homoptera (British) as far as I have observed, where the sexes differ, the ♀ is more obscure in colour than the ♂
| Ex:— | Delphax longipennis, Curt.— ♂ nearly black | ||||
| with black-spotted legs—♀ ochraceous with | |||||
| concolorous legs. | |||||
| Acocephalus | bifasciatus Lin. | } | in both the ♂ is yellow with black bands; the ♀ obscure brown not banded. | ||
| " | albifrons Lin.11 | ||||
In size the ♀ is larger than the ♂—
Sometimes the ♂ has long elytra & the ♀ short ones
Ex. Aræophus crassicornis Fab.12
JWD 20/2/68
CD annotations
Footnotes
Bibliography
Fieber, Franz Xaver. 1852. Species generis Corisa. Abhandlungen der Königlich Böhmischen Gesellschaft der Wissenschaften 7: 425–88.
Hahn, Carl Wilhelm. 1831–53. Die wanzenartigen Insecten: getreu nach der Natur abgebildet und beschrieben. 9 vols. in 5. Nürnberg: Zeh.
OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.
Summary
Notes on sexual differences in British Hemiptera.
Letter details
- Letter no.
- DCP-LETT-5904
- From
- John William Douglas
- To
- Charles Robert Darwin
- Sent from
- unstated
- Source of text
- DAR 81: 87
- Physical description
- AmemS 3pp †
Please cite as
Darwin Correspondence Project, “Letter no. 5904,” accessed on 19 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-5904.xml
Also published in The Correspondence of Charles Darwin, vol. 16
