beetles appeared in one part of Germany, the females appeared to exceed
the males as six to one. With one of the Elateridae, the males are said
to be much more numerous than the females, and two or three are often
found united with one female (84. Gunther s Record of Zoological
Literature, 1867, p. 260. On the excess of female Lucanus, ibid, p.
250. On the males of Lucanus in England, Westwood, Modern
Classification of Insects, vol. i. p. 187. On the Siagonium, ibid. p.
172.); so that here polyandry seems to prevail. With Siagonium
(Staphylinidae), in which the males are furnished with horns, the
females are far more numerous than the opposite sex. Mr. Janson stated
at the Entomological Society that the females of the bark feeding
Tomicus villosus are so common as to be a plague, whilst the males are
so rare as to be hardly known.
It is hardly worth while saying anything about the proportion of the
sexes in certain species and even groups of insects, for the males are
unknown or very rare, and the females are parthenogenetic, that is,
fertile without sexual union; examples of this are afforded by several
of the Cynipidae. (85. Walsh in The American Entomologist, vol. i.
1869, p. 103. F. Smith, Record of Zoological Lit. 1867, p. 328.) In
all the gall-making Cynipidae known to Mr. Walsh, the females are four
or five times as numerous as the males; and so it is, as he informs me,
with the gall-making Cecidomyiidae (Diptera). With some common species
of Saw-flies (Tenthredinae) Mr. F. Smith has reared hundreds of
specimens from larvae of all sizes, but has never reared a single male;
on the other hand, Curtis says (86. Farm Insects, pp. 45-46.), that
with certain species (Athalia), bred by him, the males were to the
females as six to one; whilst exactly the reverse occurred with the
mature insects of the same species caught in the fields. In the family
of bees, Hermann Muller (87. Anwendung der Darwin schen Lehre, Verh.
d. n. Jahrg., xxiv.), collected a large number of specimens of many
species, and reared others from the cocoons, and counted the sexes. He
found that the males of some species greatly exceeded the females in
number; in others the reverse occurred; and in others the two sexes
were nearly equal. But as in most cases the males emerge from the
cocoons before the females, they are at the commencement of the
breeding-season practically in excess. Muller also observed that the
relative number of the two sexes in some species differed much in
different localities. But as H. Muller has himself remarked to me,
these remarks must be received with some caution, as one sex might more
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