294 Bionomics of Weevils 



a row of eggs of gradually increasing size; anteriorly the immature ova 

 are small; but posteriorly, towards the junction of the two egg tubes with 

 the paired oviduct of each side, full-sized mature ova occur. Anteriorly 

 the egg tubes arise from an unsegmented portion called the terminal 

 chamber (Fig. 6, I, II, III, T.C. and Fig. 5, I, T.C.). The ends of the two 

 terminal chambers are united by means of the terminal filament. The 

 paired oviducts unite after a short course to form the unpaired oviduct 

 or uterus (U). On the dorsal side of the latter is a large sac, the bursa 

 copulatrix (B.C.), which projects at its anterior edge from the uterus 

 but elsewhere is united to it. The receptaculum seminis (R) is a small 

 brown chitinous vesicle curved in the form of a hook and united by a 

 slender tube to the uterus at the junction of the bursa copulatrix. A 

 small white accessory gland (A.G.) is attached to the receptaculum seminis 

 by a slender tube. The portion of the uterus below the bursa copulatrix 

 is known as the vagina. At each side of it posteriorly is a small triangular 

 chitinous plate, and before this on the ventral surface is a medium 

 chitinous rod. A semi-transparent chitinous framework occurs in the 

 ventral wall of the vagina. Attached by muscles to the central surface 

 of the vagina is a large chitinous plate known as the spiculum ventrale 

 (Fig. 5, I, S.P.). 



Development of the Female Reproductive Organs. 



On emergence from the pupa in autumn the reproductive organs of 

 the female are exceedingly small and little developed. They remain in 

 this state during the winter but growth commences in March, and by 

 April or May the reproductive organs are mature and eggs are deposited. 

 During spring and summer egg-laying is continued and the ovarian 

 tubules continue to grow, increasing to about twice the size they were 

 at the commencement of egg- laying, and to 12 times the size they were 

 during the winter. Different stages in the growth have been selected, 

 and are described below. Measurements are included to allow of com- 

 parison as to the growth of the different parts of the reproductive organs 

 but on account of individual variation they can only be taken roughly. 



Immature female, one to five months old (Fig. 6, I, and enlarged 

 Fig. 5, I). In this stage all parts of the reproductive organs are extremely 

 small, and the ovarian tubules show scarcely any development. The 

 paired oviducts are proportionately long, and the terminal filament 

 (arising from the terminal chamber) has attained its full growth. Measure- 

 ments: ovarian tubule, 0-3 mm.; terminal chamber, 0-49 mm.; uterus 

 and vagina, (Hi mm. 



