HEMIPTEKA I COCCHXE. 44! 



also employed as a dye. The Cochineal, C. cacti, Linn., 

 of Mexico, lives upon the cactus, and is collected in such 

 quantities, that 800,000 pounds of this insect have been 

 shipped to Europe in a single year. 



C. lacca, Kerr, is the species which furnishes the Indian 

 material called lac. The female attaches itself to the 

 twigs of various trees, and in this state is called stick-lac ; 

 when separated and pounded, and the greater part of the 

 coloring matter extracted, it is called seed-lac ; when 

 formed into cakes, lump-lac ; and when strained and 

 formed into thin leaves, shell-lac. 



C. manniparus, Ehren., is found on Tamarix, a large tree 

 growing on Mount Sinai, the shoots of which are covered 

 with females, which puncture them, and thus cause them 

 to discharge a gummy secretion, which quickly hardens 

 and drops from the tree, and is collected by the natives, 

 who regard it as the real manna. 



NOTONECTID^:, Latr., OR BOAT-FLY FAMILY. This 

 Family comprises hemiptera proper which are aquatic, be- 

 ing specially formed for swimming, the Fig 

 hind pair of legs being greatly elongated 

 and strongly ciliated. They are remark- 

 able for the habit of swimming on their 

 backs. They prey upon other insects. 



NEPID^:, Leach, OR SCORPION - BUG 

 FAMILY. This Family embraces aquat- 

 ic bugs which have the body oval and 

 much depressed. They are rapacious, 

 and seize their prey with the fore legs, scorpion-Bug, 

 which flex upon themselves and act as i"**** 1 "*"* 

 piercers. They can sting severely. 



HYDROMETRID.E, Leach, OR WATER-MEASURER FAMILY. 



This Family embraces hemiptera proper which have 



the body long and narrow, and which differ in their habits 



trom all the rest of the sub-order, being always found 



19* 



