The Alimentary Canal, its Appendages, Salivary Glands and the Nervous System of the adult Female Lac Insect, Laccifer lacca, Kerr (Coccidae)

Summary

Owing to the deposition of resin, the females assume two shapes, one somewhat circular in which the mouth-parts are situated ventrally about the middle of the body, and the other pyriform, in which the mouth-parts are situated at the extreme anterior end. In the former type of females the mouth-parts are posteriorly directed and in the latter anteriorly. The rostrum lies outside the body cavity between the anterior pair of oral lobes. The rostralis opens into the pharynx which lies in the tentorium. The oesophagus is elongated and passes into the colo-rectum to be succeeded by the convoluted ventriculus. The ventriculus on leaving the colo-rectum leads into the intestine, which is marked into the mid and hind intestine by the junction of the ampulla of the Malpighian tubes. The intestine after forming a loop round the greater part of the colo-rectum re-enters it close to the point of its commencement from it and continues closely attached to the outer side of the ventriculus from its distal to its proximal end; after this it comes out of the colo-rectum and runs alongside it to open into it near the anterior third of its length. The convolutions inside the colo-rectum are comprised of the ventriculus and the part of the hind intestine running outer to it. The “colon caecum” is absent. The colo-rectum opens at the anus situated at the posterior end of the insect and is divided into colon and rectum by the opening of the intestine into it.

The salivary glands consist of two branches of ovoid and spherical bodies. The common duct of the salivary gland of each side runs close to the ventral ganglion and joins the opposite duct to form the terminal duct near its anterior end, which then opens into the pharynx.

The nervous system consists of a bilobed cerebral ganglion which lies anteriorly to the mouth-parts in females in which the tentorium is directed posteriorly, and either laterally or ventrally to it in females in which the tentorium is directed anteriorly and lies at the extreme anterior end. The cerebral ganglion is joined by a pair of connectives to the ventral ganglion, which lies dorsal to the tentorium in females in which it is directed posteriorly, and posterior to the tentorium in which it is directed anteriorly and lies at the extreme anterior end. The ventral ganglion is followed by the nerve chord, which varies in length in either type of female. The main nerves arising from the central nervous system are described.