Fig. 480.—Spermatheca of the honey-bee, queen, × 40: a, space filled by a clear fluid; b, mass of spermatozoa; c, duct; d, d, active spermatozoa.— After Cheshire.
Fig. 481.—Female sexual organs of Scolytus: ER, egg-tubes; pEL, paired oviducts; ST, spermatheca; BT, copulatory pouch; KD, cement-glands; Sch, vagina.—After Lindeman, from Judeich and Nitsche.
The spermatheca.—This is a sac or pouch for the reception and storage or preservation of the semen. While in most of the higher insects it opens into the dorsal wall of the vagina (Fig. 472, f), in the cockroach, locusts, and grasshoppers it opens into the bursa; but in other European Orthoptera, as in most insects, it lies upon the dorsal wall of the vagina. (Berlese.) In the cockroach, it is a short tube dilated at the end and wound into a spiral of about one turn. “From the tube a cœcal process is given off, which may correspond with the accessory gland attached to the duct of the spermatheca in many insects (e.g. Coleoptera, Hymenoptera, and some Lepidoptera). The spermatheca is filled during copulation, and is always found to contain spermatozoa in the fertile female. The spermatozoa are no doubt passed into the genital pouch from time to time, and there fertilize the eggs descending from the ovarian tubes.” In Meloë the spermatheca is exceedingly large. (Miall and Denny, pp. 170, 171.)
The colleterial glands.—We have already briefly referred to these glands. Those of the cockroaches form a number of long blind tubes opening into the vagina. They furnish the material for the egg-capsule or oötheca, viz. chitin and large crystals of oxalate of lime.
In Phyllodromia germanica “these glands are glistening white till the time of oviposition approaches, when they assume a yellow tint, and the octahedral crystals are seen imbedded in a viscid substance which fills their lumina. This viscid substance is soluble in potassium hydrate, and is consequently not chitin. When excreted to form the oötheca, it slowly hardens, deepens in color, and becomes insoluble in potassium hydrate. Light has nothing to do with this change, which is possibly produced by the oxygen in the air. It is the same change which is undergone by the cuticula of the insect itself immediately after ecdysis.” (Wheeler.)
The vagina or uterus.—This is simply the end of the common oviduct, which, when dilated, is called the vagina, and, in the pupiparous forms, the uterus.
In the cockroach the vagina opens by a median vertical slit situated in the 8th sternite, into the genital pouch or bursa, upon the dorsal wall of which the orifice of the spermatheca is situated. In the sheep-tick the oviduct is enlarged to form the so-called uterus, which furnishes a milk-like secretion for the nourishment of the larva during its intra-uterine life.
In insects in general, the external opening of the vagina is simple, the chitinous structures (valves) at the opening being adapted to receive the male intromittent organ.
When the eggs are to be deposited deep below the surface of the earth, or in wood, or in wood-boring larvæ, or in the body of caterpillars, etc., they are inserted by the ovipositor (see p. 167).