2 
remainder very short. One very dark specimen (from Esher) had 
scarcely any tubercle at the sides of thorax, very short legs, and long 
antennae. He commented on Mr. Newbery’s exhibit which contained 
typical specimens of sericea and discolor from Scotland, Middlesex, and 
Surrey, with intermediate forms of the insects. In the discussion 
which ensued, Mr. Tutt pointed out, that it was remarkable, that the 
dark varieties of the species exhibited, were all uniformly small. Mr. 
Newbery, while agreeing entirely with Mr. Lewcock’s observations on 
sericea and discolor, said that the misapprehension concerning the 
identity of dentata and sparganii was to be attributed to the tabulation 
in Cox’s Handbook. Messrs. Cripps, Heasler, Milton, etc., also took 
part in the discussion. 
THE GENUS DONACIA, Fab. 
By G. A. LEWCOCK. 
There can be no doubt that the beetles contained in this genus 
comprise some of the handsomest examples to be found in the 
Coleopterous fauna of the British Isles. The name given to them is 
derived from the Greek word donax, which signifies a reed ; and the 
term is exceedingly applicable to this class of phytophagic beetles, as 
it implies that they are chiefly to be found among reeds, sedges, and 
such like aquatic plants. About ninety species of the group are known, 
thirty of which are found in Europe, and nineteen of the number 
inhabit this country. The larvae of the beetles feed in the stems 
of their foodplant, and are seldom or never seen by the ordinary 
collector. When full-fed, the larvae spin cocoons at the roots of 
the plant in order to undergo their next change. Like almost all other 
insects of this order, the duration of the pupal stage is exceedingly 
short, but the beetles do not leave their cocoons for some time after 
having attained the perfect condition, but remain in a state of 
hybernation until the arrival of the warm sunshine, when they crawl 
up the stems of the plants, and make their way out of the water. 
Some species are to be found early in May, others in June, July, 
August, September, and even as late as October. As previously 
observed, they are essentially lovers of the bright sunshine, but the 
month of the roses is certainly the most favourable time for obtaining 
them, as they prefer the hottest weather wherein to take their sport and 
pastime. At this period of the year, they may be observed by anyone 
who cares to seek them, flitting from stem to stem in the reedy places, 
or skimming over the broad floating leaves of various water plants—the 
leaves of Nymphcea alba and Potamogeton natans being their special 
resort, and it is on the latter plants where I have chiefly found them. 
The British species are divided into two major groups by Fowler 
(Coleoptera of British Isles), as follows :— 
1. Tibiae not produced externally into a tooth at apex ; apex 
of mandibles only slightly projecting beyond labrum; first seg¬ 
ment of abdomen longer than the rest taken together. 
2. Tibiae produced externally into a tooth at apex; mandibles 
stout, projecting considerably beyond labrum; first segment of 
abdomen equal to, or rather shorter than, the remainder taken 
together. 
