] 02 Weevils of the Genus Sitona 



the field, but similar experiments tend to show that Sitona take longer 

 to develop when bred in captivity. 



Habits. 



During fine weather in September and October the beetles are 

 most abundant and may be obtained by sweeping clover or lucerne. 

 They are very active" on sunny days at this time of the year and are 

 frequently to be met with on pahngs or stone walls. It is probable that 

 the principal migration to the new fields occurs at this time. At Invershin, 

 Sutherland, from September 16th to 21st, 1920, several hundred beetles 

 of this species were observed upon the walls of a wooden building 

 adjoining fields of grass and hay. On sunny afternoons numbers were 

 seen crawUng up from the ground, but despite careful watching I failed 

 to observe any specimens flying on to the wall, although all the specimens 

 examined from this locahty proved to have fully developed wings. The 

 weevils dropped down from the woodwork at the slightest touch. They 

 were equally common on the walls in the shade as in the sun, but were 

 rare on the stonework of the house. Many got in at the windows. Sitona 

 sulcifrons, a very common species with brachypterous wings also oc- 

 curred upon the walls but in much fewer numbers. The following year 

 on revisiting this district on a fine day on September 21st no such swarms 

 were observed, though the weevils were very common on the clover. 

 This activity of the imagines in autumn is not confined to the winged 

 individuals, but has also been observed in brachypterous specimens at 

 Swordale, Ross-shire. In France, Bedel (3) has made some interesting 

 observations upon a migration of Sitona gemellata in the end of September 

 and beginning of October. 



In the winter the adults of the S. hispidula continue to feed, and even 

 during continuous frost in January and February, they were to be found 

 in the fields in Ross-shire lying on the surface of the ground beneath 

 freshly eaten clover leaves. On sunny days in March and April the 

 beetles may be seen walking on the clover leaves but are more frequently 

 taken at the base of the plant. They are also active at night. They lay 

 their eggs indiscriminately wherever they happen to be resting. 



Number of eggs laid. The number of eggs laid by a single female from 

 the commencement to the end of oviposition has not been ascertained, 

 but the following experiments carried out in the laboratory show the 

 number of eggs laid by two females after hibernation. Artificial con- 

 ditions are doubtless responsible for the greatly prolonged life of the 

 female in the first experiment. This has happened with other Sitona 



