DEVELOPMENT OF TRICHOGRAMMA EVANESOENS. 151 
reeds which grow from shallow ponds and the sides of 
streams ; they may be observed copulating and laying their 
eggs. The latter are laid in masses in a regular manner, the 
whole group forming a rectangular mass containing a varying 
number of eggs. In one mass eggs of several shades of 
brown may occur in patches, as if a number of beetles had 
oviposited in the same place. Whether this is so I do not 
know. The egg groups do not adhere very closely to the 
surface of the reed, and they are easily removed by bending 
the surface upon which they are laid. From the number of 
parasitized eggs which one can find there is no doubt that 
this Trichogrammid must cause a great deal of destruction 
among the broods of beetles, and were the Donacia a pest on 
valuable plants it would be quite easy and worth while to 
rear batches of parasites. This has been done in the case 
of parasites of injurious insects, particularly in America, and 
such methods of attacking pests have so far met with a good 
deal of success. In the case of Donacia almost the entire 
number of eggs laid in a locality where the parasites are 
common will be found parasitised. In PI. 10, fig. 3, is drawn 
an enlarged figure of Donacia simplex; in A the egg 
mass (OF.) viewed in profile upon the reed (P.) is shown, 
and resting on the lower eggs a Trichogramma (P.P.) is seen, 
drawn to about the same scale as the beetle. 
The Parasite (Trichogramma evanescens, Westw.) 
I have to thank Commander Walker for drawing my 
attention to some literature on Trichogramma. The Rev. J. 
Waterston, B.D., of the Imperial Bureau of Entomology, in 
kindly identifying this insect, writes that Trichogramma 
evanesce ns is generally found as a parasite upon the eggs 
of insects whose habits and place of oviposition are similar to 
that of Donacia. 
As is common with many of the parasitic Hymenoptera, 
Trichogramma evanescens has very gaudy colouring. 
The wings, which are a shiny blue, at once attract attention 
