ORDER HEMIPTERA. 8 I 



about three-quarters of an inch in length, and found on oak 

 trees. 



Family T^JassidcB. — This family contains a considerable num- 

 ber of small insects, some of them of great beauty and elegant in 

 appearance. The typical genus \s/assiis. 



Family 8, Psyllidce. — This is the first family of the so-called 

 " Plant Lice " or " Blight." They resemble the " Froghoppers " 



Fig. III. — ByihoscopusVenosus. (Mag,) 



in their habits of jumping. Most of them are small insects, and 

 they subsist on the sap of plants, to which they are sometimes in- 

 jurious. A few species produce galls. 



Livia pyri IS a reddish insect, abundant on pear trees. Other 

 common species are found on the alder, ash, oak, and nettle. 



Fig. 112. — I^via Juncorum (Mag.) 



Family 9, Aphidce. — The Aphidce, or " Plant Lice," " Blight," 

 and " Green Fly," as they are variously called, are amongst the 

 most destructive of insects. They are small and feeble creatures, 

 but make up for their individual insignificance by their immense 

 numbers. 



They sometimes exist in countless millions, completely smother- 

 ing the plants upon which they feed. 



Migratory habits seem to be strongly developed among the 

 AphidcB, hence it is we are so suddenly visited by such enormous 

 quantities of the insects during hot weather in the summer time. 



In colour the Aphides are generally green, brown, and black, 



