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Our knowledge as to how the other insects place their eggs, 
as well as to what cutting apparatus they have to place 
their eggs with etc. is too poor. That these eggs are well 
concealed is evident from the antennæ of the imagines, 
which are provided with quantities of sense organs, sense- 
hairs, sense spots and the like. And when considering 
that these insects are so amply furnished, it is not sur- 
prising that the human eye is unable to discover the eggs. 
The long ovipositor of many of the species also tends 
to the belief that the eggs are laid deep in the texture of 
the plants. But by degrees as the biology of these small 
Hymenoptera becomes better known it will be proved that 
they are not nearly as rare as was originally supposed. 
Thus at the present time, certain species are only taken 
singly in very widespread localities, others only singly in 
localities of the size of a few square meters, and again 
some few in only a single specimen at quite accidental 
spots. One species, Trichogramma evanescens, on the other 
hand is to be found at all small ponds etc. when it is 
discovered that it preys on the eggs of Sialis, Stratio- 
midae, Chrysops, Aterix and Tabanus as well as Nonagria 
(2). That all the species attack eggs it not very probable, 
as it is well known that the Encyrtide chiefly attack Coccus, 
but at the same time certain species attack also Lepido- 
pterous larve, and thus no doubt it will be proved to 
be the case with the 7richogrammine that certain of these 
species deviate from the rule of attacking the eggs. 
Most of the species, however, are only to be taken 
with the sweepnet; but at this work two great difficulties 
present themselves, the first being that the species are so 
extremely small that it requires a very trained eye to 
discover them and next that they live in the grass most 
probably at the very bottom, for which reason with a single 
sweeping very little results. The best means is to use a 
large sweep net; mine is 1 meter deep and 1,2 meter in 
