NOTES ON DRAGONFLY PARASITES. 243 
legs. All known species of Acari belonging to the genus 
Canestrinia, Berlese, are found upon insects, and mostly upon 
Coleoptera ; numerous Gamaside, when in the immature stages, 
are found wholly or chiefly upon Coleoptera. Prof. C. V. Riley 
has published an interesting account (‘American Naturalist,’ 
xil. p. 189, 1878) of his researches into the life-history of the 
North American locust-mite, to which he gives the name T'rom- 
bidium locustarum. Speaking of the newly-hatched larve, he 
says: ‘‘ These little six-legged specks crawl upon the locusts and 
fasten to them, mostly at the base of the wings or along their 
principal veins.” He adds: ‘‘ That they are often so numerous 
as to weaken and kill their victim, reports clearly prove.” Most 
aquatic Rhynchota are subject to the attacks of water-mites, and 
Prof. Riley says that over five hundred have sometimes been 
counted on a single specimen of Zaitha (Belostoma) fluminea, 
Say, a large American species. Coming to the Neuroptera, we 
may cite a female scorpionfly (Panorpa germanica) taken by 
ourselves in Epping Forest, and having a mite located on the 
under side of the right hind wing. 
It must, however, always be remembered that the word 
‘parasitic’ is used in different senses by various writers, and 
that the meaning of the word as used by most biologists is wider 
in its signification than that attached to it by the popular idea. 
It is necessary to remember this when dealing with the Acari, 
as so many of that group of creatures, particularly in the imma- 
ture stages, seek only conveyance from the host on which they 
are found, and not nourishment ; the parasitism being temporary 
and apparently for the purpose of the distribution of the species 
of mites: this is chiefly confined to terrestrial Acari, as far-as is 
at present known. There are numerous other variations in the 
nature of the relations of the so-called Acarine parasite to the 
host upon which it is found. 
Although water-mites attach themselves so freely to many 
kinds of aquatic insects, we have not yet met with any instance of 
a nymphal dragonfly being attacked by them. Weare acquainted 
with eases in which Acari have attacked imaginal dragonflies 
belonging to the sub-families Libelluline, Gomphine, and 
Agrionine. Among the Libelluline, Sympetrum meridionale is 
a notorious instance: indeed, McLachlan wrote of it that “its 
liability to have the well-known red Acari attached to the wings 
(sometimes in enormous numbers) is so marked as to be almost 
a specific character of the insect itself, few specimens being en- 
tirely free from them” (Ent. Mo. Mag. xx. p. 253, 1884). ‘Thir- 
teen examples of this species taken casually in France were ex- 
hibited by Mr. McLachlan at a meeting of the Entomological 
Society of London. Only one of them had escaped attack, but the 
remaining twelve carried between them no fewer than four hun- 
dred and eighty-one parasites. Single specimens had as many as 
x 2 
