. Economic entomology. Beneficial insects; Insect pests; Thysanura. WATER MITES. ^51 timate large, and the last armed with spines. The feet are long and slender and ciliated, except the two last, which are only pilose. Its colour is pale red, and its size about that of a mustard seed. Genus Hydrachna. The genus is restricted by Duges to those fresh water mites that have palpi with the third joint largest, a beak of the same length as the palpi, and mandibles with sharp blades. Their transformations have been fully observed, and are very interesting. From the eggs which have been laid in spring
. Economic entomology. Beneficial insects; Insect pests; Thysanura. WATER MITES. ^51 timate large, and the last armed with spines. The feet are long and slender and ciliated, except the two last, which are only pilose. Its colour is pale red, and its size about that of a mustard seed. Genus Hydrachna. The genus is restricted by Duges to those fresh water mites that have palpi with the third joint largest, a beak of the same length as the palpi, and mandibles with sharp blades. Their transformations have been fully observed, and are very interesting. From the eggs which have been laid in spring in the stems of water plants, perforated for the purpose, little hexapod animals come to view, with a large heart-shaped sucker in front, which might be taken for a head, but that the eyes are situate behind it on the anterior margin of the back. Subsequently they attach tJiemselves to different water insects (Nepa, Ranatra, Dytiscus, &c.); and whilst the abdomen is growing and extending itself into an elongated sac, the feet and the sucker remain of the same size. After a time, however, the feet drop off, and the creature remains like a bag hanging from the insect to which it is affixed. For long these bags were thought to be the eggs of the Nepa, and it was described as being like the frog of Surinam, that laid its eggs on its ov/n back, and hatched them out of its skin. This stage corresponds apparently to that of the pupa in other insects, the perfect insect being formed within the skin, like a fly in its pupa. The wood cuts show its various stages in the species. Hydrachna globulus, now Hydrochoreutes globulus, a little further Enlarged sketch of hinder part of abdomen of Nepa cinerea, with nymphs of Hydrachna adhering to Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Murray, Andrew, 181
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