244 THE ENTOMOLOGIST. 
seventy-three, ninety-six, or even one hundred and eleven of them. 
‘‘They were firmly fixed on the nervures towards, and at, the 
base of the wing, and almost (but not quite) invariably on the 
under side, and whatever might be the number on any particular 
dragonfly it was always divided nearly symmetrically on the 
two sides of the insect, those much infested having a very pretty 
appearance, from the wings appearing as if spotted with blood- 
red’’ (Ent. Mo. Mag. xiii. p. 95, 1876). Two excellent plates ac- 
company a paper by M. Krendovsky on the economy of the larve of 
Hydrachnide published in a Russian periodical (Trud. Charkov 
Uniy., 1878, Tom. xii, pp. 221-286). Figure 7 on Plate 1 shows 
a specimen of S. meridionale having numerous mites, coloured 
red, distributed in a remarkably symmetrical manner along the 
principal nervures of the wings. Another figure (8) on the same 
plate represents, again in colour, three of the mites on a large 
scale. These mites are described as the six-legged larve of 
Arrhenurus papillator (Mull.), but, as will appear later, this 
determination is by no means certain. 
Krendovsky also states that Hydrachnid larve occur on the 
sternum of S. flaveolum. This is the only case which has come 
to our knowledge in which larve have been found on the body 
of an Anisopterid dragonfly. Some of the specimens of S. fons- 
colombu taken by Mr. C. A. Briggs in Surrey in 1892 were much 
affected by a dark carmine-coloured Acarus; on one of the 
dragonflies he counted as many as eighty-five parasites. Mr. 
Briggs asks, ‘‘Do these Acari extract any colouring matter from 
their host ? They exactly match the colouring of the nervures, 
and one that I squeezed gave out a similar coloured fluid” 
(Ent. Mo. Mag., ss. iii. p. 194, 1892). SS. striolatum has also 
been mentioned in this connection, but apparently in error for 
S. meridionale. 
An example among the Gomphine is afforded by a female of 
Platygomphus dolabratus from India in the British Museum, 
which has a red parasite on the left hind wing. 
But it is among the Agrionine that Acari are met with most 
abundantly, and our own collection furnishes examples of six 
species which are infested to a greater or smaller extent. Those 
species are Hrythromma naias, Pyrrhosoma nymphula, Ischnura 
elegans, Agrion pulchellum, A. puella, and Enallagma cyathigerum. 
We have also noticed an immature female of P. tenellum in the 
Stephens cabinet carrying a single mite on the sternum. 
Furthermore, Krendovsky includes Lestes in the category of 
mite-attacked dragonflies. In all the cases which have come 
under our personal observation, the parasites are attached to the 
under side of the thorax or abdomen, or both (but never to the 
wings), sometimes in twos and threes, sometimes covering the 
entire surface affected. In life they appear to the unaided eye 
as globose bodies less than a millimetre in diameter when fully 
