HEMIPTERA HOMOPTERA. NEUROPTERA. 701 



quently stationary on their food-plants, and covered by scales of vari- 

 ous forms, composed of cast skins, secretions, etc. 



As a rule Scale-insects are seen in the form of these scales attached 

 to fruit, leaves or bark. Under the scale the female lives and lays her eggs. 

 Some species form no scale and are then usually coated with a waxy efflor- 

 escence, and are termed " mealy-bugs." The females are very prolific and 

 parthenogenesis exists but not to the extent formerly thought when the 

 males were less well known. Many of the products of scale -insects have a 

 commercial value. Ceroplastes ceriferus in India and Ericerus pela in China 

 produce white wax, Carteria lacca forms lac. Kermes and Porphyrophora 

 afford a red dye, and Coccus cacti (Fig. 445) is the well-known cochineal 

 insect. On the other hand many are injurious to plants : some render 

 the leaves sticky by copious secretions of honey-dew. Mytilaspis forms 

 the " oyster-shell " scale on orchard trees. Aspidiotus attacks oranges, and 

 there are many others which infest fruit-trees, etc. 



Group IV. ENDOPTERYGOTA. 



The wings arise by imaginations of the hypodermis. and for 

 sometime remain tucked in the body. Complete metamorphosis. 



Order 15. NEUROPTERA.* 



Carnivorous insects with biting mouth parts ; jour membranous 

 wings with many cross-nervures ; antennae large. Complete 

 metamorphosis with as a rule an cruciform larva. 



The Order Neuroptera has been much diminished in recent 

 years by the recognition of the ordinal value of many of the 

 families which at one time were included in it. Some species 

 have aquatic larvae, but the majority are terrestrial. On the 

 whole the Order is a beneficent one as far as man is concerned 

 inasmuch as its members eschew plants and many of them 

 devour injurious insects. The Order is divided into nine 

 families f : 



Fam. 1. Sialidae. A squarish head bearing long antennae. Four 

 wings which when at rest are unfolded and meet at an angle. Fairly 

 numerous nervures break up the wings into many irregular cells. The larva 

 has powerful mandibles and the pupa is quiescent. The Alder-flies com- 

 prise but five genera. They haunt the trees and shrubs along the banks 

 of streams. Sialis lutaria is a favourite fly with fishermen and is one of 

 the commonest insects in Britain. The eggs are laid in masses of two or 

 three thousand on rushes, grass-stems, etc. The larvae have a pair of 



* Dufour, Ann. Sci. Nat. (3), ix, ZooL, 1848, p. 91. Loew, Linnaea Entomo- 

 logica, iii, 1848. Hagen, Stettin Ent. Zeit., xxvii, 1866, and P. Boston 

 Soc., xv, 1873, p. 263. 



t The Neuroptera as here restricted are equivalent to the Planipennia 

 minus the Panorpidae (Mecaptora). 



