PHYLUM ARTHROPODA. INSECTS 



255 



one pound of silk. The number of silkworms 

 that are working for man is indicated by the 

 fact that about 50 million pounds of silk are 

 used in the world every year. Lac insects 



belong to the family Coccidae; they secrete 

 a wax known as shellac. The dye known as 

 cochineal is made from the dried bodies of 

 a scale insect that lives on cactus; it is no 





Aphislion 

 (Neuropfera) 



Antlion lying in 

 wait at bottom 

 of its pit 



* -./ 



Ground beetle 



Tiger beetle 



Australian 

 ladybird beetle 



O'i* 



Antlion 

 (Neuroptera) 



-Coleoptera- 



Figure 154. Beneficial insects. The figures are not drawn to scale. (After U.S. Department of 

 Agriculture Yearbook, 1952.) 



longer of much value, aniline dyes having 

 largely taken its place. 



Bees are among the most valuable of the 

 insects that pollenize flowers. For example. 



apples, pears, blackberries, raspberries, and 

 clover depend upon them. Certain other in- 

 sects also perform this important function. 

 This means that many of our important food 



