1891-92.] Dragon- Flies : their Life- History. y 



needles," a distinct allusion to the elongated abdomen ; also 

 " Horse-stingers," from a notion that they attacked and stung 

 horses, — but they have no sting, and are in this respect harm- 

 less. In France they are termed " Demoiselles," in allusion 

 to their beauty; in Germany, "Water -virgins," and also 

 "Gauze-flies." 



The perfect insect has a round lengthened body, with large 

 wings, and among the different species there is great diversity 

 both in size and colour. There is also frequent dissimilarity 

 in the colours of the male and female. For instance, the male 

 of Agrion puella — a beautiful slender insect, measuring from 

 2 inches to 2 J inches across the wings — is azure blue, but 

 the female is almost black. The specimen shown, in spirit, 

 Agrion minium, from Balerno Moss, where I saw it in dozens, 

 is of a brilliant scarlet colour, touched with black and yellow 

 beneath, with black wings alike in size. Libellula depressa, 

 about 2 inches long, is of a beautiful blue colour. Aeschna 

 grandis, nearly 3 inches long and 4 inches in expanse of wings, 

 is of a light yellow colour. The eyes in the largest species 

 especially are simply marvels of colour, and the wings of many 

 are curiously tipped with different hues. These beautiful tints, 

 however, all vanish after death. 



The head of the dragon-fly is comparatively small, and 

 differently shaped in the different families. It is excavated 

 posteriorly, and its connection with the prothorax is so slight 

 that it almost turns on it as on a pivot. In front of the eyes 

 is a portion termed the vertex, which sometimes (as in Libell- 

 ulida?) forms a swollen vesicle. The antennae are minute, and 

 generally smaller in proportion than in almost any other insects, 

 consisting of only two short swollen basal joints, and a five- or 

 six-jointed bristle-like thread. In some foreign species they 

 are fairly prominent. The front of the head is vertical, and 

 consists of a large, often dilated, upper portion, commonly 

 termed the nasus, followed by a transverse portion termed 

 the rhinarium, and this again by the large labrum, which 

 conceals the jaws and inner mouth parts. The lower lip or 

 labium is attached to a very small chin piece (or mentum), 

 and is generally very large, — often (as in Agrionidte) divided 

 almost to its base into two portions, or more frequently entire 

 or nearly so. On each side of the labium are two usually 



