92 THE INSECT WORLD. 
illustrious Swedish naturalist, De Geer, because our young readers 
have most likely met with this insect, or will do so some day 
when gathering raspberries. 
The Grey Pentatoma, marked with black, yellow, and red, is to 
be found throughout the whole of Europe in cultivated fields and 
gardens, sometimes also on the trunks of large trees, especially 
elms. This species, in common with the greater part of those 
which compose the group we are describing, emits a smell when 
irritated or menaced with some danger. At other times no odour 
will be noticed. Let us hear what M. Léon Dufour says on this 
subject. 
“Seize the Pentatoma with a pair of pincers and plunge it into 
a glass of clear water; look through a magnifying-glass, and you 
will see innumerable small globules arising from its body, which, 
bursting on the surface of the water, exhale that odour which 
is so disagreeable. This vapour, which is essentially acrid, if it 
touch the eyes, causes a considerable amount of irritation. If 
one of these insects is held between the fingers, so as not to stop 
up the odoriferous orifices, and to cause this vapour to touch a 
part of the skin, a spot, either brown or livid, will ensue on 
that part, which lotions, though repeatedly applied, will at first 
fail to remove, and which produces in the cutaneous tissue an 
alteration similar to that which succeeds the application of mineral 
acids.” } 
The disagreeable smell exhaled by different species of Penta- 
toma is the result of a fluid secreted by a single pear-shaped gland, 
either red or yellow, which occupies the centre of the thorax, and 
which terminates between the hind legs. 
With the Syromastes, which are bugs of this same section, the 
secretion has, on the contrary, an agreeable smell, which reminds 
one of that of apples. Many kinds of Pentatoma are destructive 
to agriculture. Others, however, attack the destructive insects, 
and ought therefore to be carefully spared. We will mention in 
this case the Blue Pentatoma, which kills the Altica* of the vine. 
There may be observed, at the foot and about the lower part of 
trees, or at the base of walls exposed to the mid-day sun, groups 
of fifty or sixty small insects pressed close to each other, and often 
* A genus of beetles. 
