104 Weevils of the Genus Sitona 



October 12th. December 5th — soil of pot thoroughly searched but no 

 larvae found. 



(6) The Spring Hatching Larvae. 



Eggs laid Results 



Sept. 17th to Oct. I8th, 1919 Aug. .31s/, 1920. Imagines emerged. 



Oct. and Nov., 1919 Ju7ie 2nd, 1920. Larvae 2-2-3-3 mm. long 



occurring 1 or 2 inches below the surface 

 soil, close to the small fibrous roots, and 

 destroying the root nodules. 

 „ „ Jiily 3rt/, 1920. Larvae half to full grown. 



Injuring main root of clover. 

 „ „ July, end. Pupae. 



„ „ Aug. I9th. Imagines. 



Larval period. 15-lG weeks. 



2. Development of the Spring and Summer Laid Eggs. 



Eggs laid Results 



Apr. 14th to 24th, 1919^ June lUh. Larvae 1-6 mm. long to 2-7 mm. 



„ „ July 9th. Larvae 2-5-3-5 mm. 



„ „ July 2Sth. Fully grown larvae. 



„ „ Aug. 12th. Pupae. 



„ „ Aug. 26th to Sept. 1st. Imagines. 



Larval period. About 11 weeks. 

 May, 1919 Sept. llth. Imagmes. 



June 21st to July 2\s,V- Oct. 31s<. Full grown larvae. Pupae. 



Nov. 2Sth. Pupae. Failed to rear adults. 



The above experiments have been carried out in Ross-shire. It is 

 probable that in the south of England the larvae develop more rapidly, 

 as in fields at Wye, Kent, full grown larvae and pupae of this species 

 were found on June 15th, from which imagines were reared from the 

 beginning to the 21st July. From the field in Ross-shire pupae were 

 obtained from July 5th to August llth and adults reared from them from 

 the end of July to the end of August, It was noticed that when larvae 

 were reared in Ross-shire in a glass-house, the temperature being raised by 

 the sun alone, the larval period occupied only eight weeks. During the 

 winter and early spring repeated search was made for larvae of this 

 species both in the south of England and the north of Scotland in 

 locaUties where the adult was common, but always without success; 

 Sitona puncticollis and S. jlavescens being the only species found in the 

 larval stage at that time. 



Life-History in America. 



In America, according to Wildermuth(22) the hfe cycle of this species 

 occupies a very much shorter time. Thus the egg stage lasts 13 days, the 



^ These eggs were placed at the roots of clover previously planted out of doors in one 

 of the large breeding cages already described (10, pp. 283-284, Plate XIX). 



