•270 Bionomics of Weevils 



find out the life-history of the different .species which abound on legu- 

 minous crops in Britain, and at the same time to ascertain the nature 

 and extent of the damage done by each in both the larval and adult 

 stages. I have only concerned myself with those species which I have 

 found present on crops in sufficient number to cause injury and these 

 consist of the following: S. lineatus L., puncticollis Steph., flavescens 

 Marsh., suldfrons Thun., hispidulus ¥., humeralis Steph. and crinitus 

 Herbst. 



By means of the following key which I have adapted with some 

 alterations from Fowler's (15) I have Endeavoured to make it easier to 

 distinguish each injurious species from the other and also from the re- 

 maining species of the genus. As it is exceedingly difficult to form a 

 satisfactory table to separate species which have such a close general 

 resemblance I add figures of the species concerned which I hope will 

 supplement the key. Each species will be described in detail when dealt 

 with. 



Key to the British Species of the Genus Sitones found on 

 Leguminous ( 'rops 1 . 

 (The injurious species are marked with an asterisk.) 



I. Size large 6-9 mm. ; elytra long and tapering towards the extremity which is 

 pointed. Scutellum usually very conspicuous with two white tufts of hair which 

 diverge in front and cause it to appear emarginate . . . . S. griseus F. 



II. Size 2-6 mm. ; if large, elytra not relatively long or tapering towards extremity, 

 i. Elytra, if viewed sideways, with very distinct raised setae which are more or 



less erect. 



1. Thorax convex and arched forming a distinct angle with the elytra if viewed 

 sideways-, sides of thorax strongly rounded; eyes prominent; outstanding 

 setae very long S. regensteinensis Herbst. 



2. Thorax not convex or arched, almost on same level as elytra. 



A. Eyes flat, body thickset and compact, thorax with large diffuse punctures 

 and the sides moderately strongly rounded 



*S. hispidulus F. (Plate XIV, Fig. 6). 



B. Eyes very prominent. Thorax with sides slightly rounded. 



a. Eyes extremely prominent projecting almost on a line with the shoulders, 



bristles a little more depressed, scales of elytra narrower, punctuation 



of thorax coarser and more diffuse . . . . S. W aterhousei Walt. 



I>. Eyes prominent but not projecting nearly to line of shoulders; scales 



of elytra broader and bristles more erect; punctuation of thorax finer 



and closer *S. crinitus Herbst. (Fig. 3). 



ii. Elytra, if viewed sideways, with fine raised setae or hairs which are depressed 

 towards the apex but are distinct from the general pubescence. Size small. 



1 A', cylindricollis Fahraeus ( = melihti Walton) has been omitted from this key on 

 account of its .scanty distribution and local habits. 



