Behaviour of Coleoptera in time of Floods. 381 
of the flood. It is worth noting here how very soon many 
of the beetles leave this rubbish when it touches the ground 
on the subsidence of the flood. I make a rule now, when 
collecting flood refuse, of always taking it at the height 
of the flood, while it is floating on the water. From 
some rubbish fished out of the Kennet in 1908 I took 
about thirty specimens of Ilyobates forticornis. On col¬ 
lecting about the same quantity two days after, when the 
water had subsided and left it resting on the ground, only 
five or six more specimens were obtained. No doubt there 
is a large death-rate at every flood, some beetles soon 
succumbing to their wetting. It is difficult to account for 
the absence of certain species one would expect to find 
in the rubbish, particularly Anehomenus albipes and Oodes 
helopioides. The former is a very abundant riverside 
species, yet it quite seldom turns up in flood refuse. 
The latter I have never taken in this way, although it is 
a common species in the Kennet valley, and Commander 
Walker remarks on this (Ent. Mo, Mag., Vol. xliv, p. 135) 
with regard to the Thames. 
But apart from the help of the wind many waterside 
beetles have other methods of reaching the shore quickly, 
viz. by swimming in various ways, walking on the surface 
of the water, and by this curious method described by 
MM,G. Billard and G. Bruyant, which,for want of abetter 
term, I will call “skimming.” 
Now let us return to Dianous coeruleseens. It is in this 
species that this method of progression is perhaps most 
easily watched, as it so readily performs it. When a piece 
of wet moss from near a waterfall is entirely immersed in 
water this beetle may sometimes be seen, covered with a 
glittering silvery layer of air, walking quite easily on the 
moss. At other times the beetle crawls to the outside of 
the moss and floats to the surface of the water, back upper¬ 
most, doubled up in the form of an inverted n> with the 
legs folded in front of the abdomen. The elytra first reach 
the surface and are soon free of the water. The thorax 
and head then clear the water and dry; the body is then 
straightened, with the apex pointing slightly upwards, the 
base of the abdomen sometimes taking some time to dry. 
Now the whole of the upper surface is above water and 
dry, the anal end being just at the surface, and the whole 
of the imderparts and legs being under water. The beetle 
then generally starts off “skimming” at a most remark- 
c c 2 
