92 THE INSECT WOELD. 



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. L6on Dufour says on this 

 subject. 



" Seize the pentatoma with a pair of pincers and plunge it into 

 a glass of clear water ; examine it through the magnify ing- glass, 

 and you will see innumerable small globules arising from 

 its body, which, on exploding on the surface, at once 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 suc- 

 ceeds the application of mineral acids." 



The disagreeable smell exhaled by different species of Pentatoma 

 is the result of a fluid secreted by a single gland, of pyramidal 

 form, and either red or yellow, which occupies the centre of the 

 thorax, and which terminates between the hind feet. 



With the Syromastes, which are bugs of this same group, 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. ED. 



