Dorothy J. Jackson 289 



but on May 10th ten of the weevils were alive and active and commenced 

 laying eggs on May 1 7th. 



With the first warm days of spring the weevils leave their winter 

 quarters and migrate to peas and beans and there commence their 

 destructive work. 



The length of life cycle of an average individual may be thus sum- 

 marised: egg 3 weeks, larva 7 weeks, pupa 3 weeks, imago 12 months = 

 Total 15 months. 



The months during which the weevil occurs in its different stages 

 in Scotland and England may be tabulated as follows: 



Kent Ross-shire 



Egg Stage April and .May diminishing Juno May and June diminishing July 



Larval stage May to beginning July End June and July diminishing 



August and September 



Pupal stage June and July End duly to September 



[maginal stage .Inly to duly August to August 



The Reproductive Organs of Sitones lineatus. 



The reproductive organs of the newly emerged weevils are immature, 

 particularly those of the female, which have to develop to four times 

 their original size before egg-laying can take place. Tbe male organs also 

 undergo development but not to the same extent. 



Description of the Reproductive Organs of the Mature Male. (Fig. 5, III.) 



The male reproductive organs comprise testes, paired vasa deferentia, 

 seminal vesicles, and seminal tubes, unpaired vas deferens or common 

 duct and the internal sac. The latter has the appearance of being more 

 or less surrounded by cbitinous parts, consisting of tegmen and median 

 lobe, which in reality form with the internal sac and connecting mem- 

 branes a continuous tube inverted when not in use. 



The testes are conspicuous yellow bodies lying one on each side of 

 the body beneath the third, fourth, and fifth abdominal tergites. In 

 their natural position the posterior part of the colon and rectum of the 

 alimentary canal lie between the testes, but are dorsal to the vasa 

 deferentia. Underneath the alimentary canal the struts of the median 

 lobe project between the testes posteriorly. Tbe testes of the mature 

 male measure 1 mm. long by 0-85 mm. broad. Viewed dorsally the testes 

 are oval and lobed in outline but are compressed dorso-ventrally (see 

 Fig. 5, II, T). They are covered by a tbin membrane which supports 

 tracheae and strands of fat body, tbe latter imparling a yellow colour 

 to the testes viewed as a whole. 



