12 
INTRODUCTION. 
yceidee, OimicidcB, Reduviadce, Hydrometradce, Ntpadce [Plate I. 
Fig. 1, Nepa apiculata], and Notonectadee) live entirely on the 
juices of animals, and by this means destroy great numbers of 
noxious insects ; some are of much service in the arts, affording us 
the costly cochineal, scarlet grain, lac, and manna ; but the benefits 
derived from these are more than counterbalanced by the injuries 
committed by the domestic kinds, and by the numerous tribes of 
plant-bugs, locusts or cicada;, tree-hoppers, plant-lice, bark-licc, 
mealy bugs, and the like, that suck the juices of plants, and re- 
quire the greatest care and watchfulness on our part to keep them 
in check. 
4. Nf.uroptera ( Dragon-flies , Lace-winged flies; May- 
flies , Ant-lion , Day-fly , White Ants, <fe.). Insects with jaws, 
four netted wings, of which the hinder ones are the largest, 
and no sting or piercer. Transformation complete, or partial. 
Larva and pupa various. 
The white ants, wood-lice, and wood-ticks, ( Termitidce and 
Psocidce,) the latter including also the little ominous death-watch, 
are almost the only noxious insects in the order, and even these 
do not injure living plants. The dragon-flies, or, as they are com- 
monly called in this country, devil’s-needles ( Libelluladce ), (Figs. 
4, 5,) (Plate I. Fig. 2, Agrion basalis,) prey upon gnats and 
mosquitoes ; and their larva; and pupa;, as well as those of the 
day-flies ( Ephemeradce ), semblians ( Semblididce ), and those of 
some of the May-flies, called caddis-worms ( Phryganeadce ), (Fig. 
6,) all of which live in the water, devour aquatic insects. The 
predaceous habits of the ant-lions ( Myrmeleontidce ), (Fig. 7,) 
have been often described. The lace-winged flies ( Hemerobi - 
adee), (Fig. 8,) in the larva state, live wholly on plant-lice, great 
numbers of which they destroy. The mantispians ( Mantispa - 
dee), and the scorpion-flies ( Panorpadce ), are also predaceous 
insects. 
5. Leridoptera ( Butterflies and Moths'). Mouth with a 
spiral sucking-tube ; wings four, covered with branny scales. 
Transformation complete. The larvae are caterpillars, and 
have six true legs, and from four to ten fleshy prop-legs. 
