[20] From [Greek: hydôr], water, and [Greek: koris], a bug. The land bugs consist of a great number of kinds, which, for the most part, are of little interest. We will only mention here the _Peniatomidæ_, commonly known as Wood Bugs; the _Lygæi_, Bugs, properly so called; the _Reduvii_, and the _Hydrometræ_. The _Pentatomidæ_, which comprise many genera, include the wood bugs of most authors. They are to be found on plants and trees. They fly quickly, but only for a short time. The Ornamented Pentatoma (_Strachia_ [_Pentatoma_] _ornata_), known as the Red Cabbage Bug, is very commonly found on the cabbage, and on most of the cruciferous plants. It is variegated with red and black, and its colours are subject to numerous variations. The Grey Pentatoma (_Raphigaster griseus_), Fig. 69, is common throughout the whole of Europe. In autumn these bugs are frequently to be found on raspberries, to which they impart their disagreeable smell. They are also to be found in quantities on the mullein, when that plant is in flower. The upper parts of the head are of a greyish brown, and are sometimes slightly purple. The coriaceous part of the hemelytra is of a purple tint, but the membranous part is brown. All these parts are covered with black spots, which are only to be seen with a magnifying-glass. The wings are blackish. The under part of the whole body and the feet are of a light and rather yellowish grey, with a considerable number of small black spots. The abdomen is black above; and it is bordered with alternate black and white spots. [Illustration: Fig. 69.--Grey Pentatoma (_Raphigaster griseus_).] We have repeated here the description given of this bug by the 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 by some danger. At other times no odour will be noticed. Let us hear what M. Léon Dufour says on this subject.