66 



ANIMALS OF LAND AND SEA 



zation of the abundance of these creatures and their potental- 

 ity for rapid increase. In Cyprus in 1881 egg cases of grass- 

 hoppers to the number of 1,600,000,000 and weighing 1,300 tons 

 were destroyed with apparently Httle effect upon the species. 

 A swarm of these insects that passed over the Red Sea in 

 1889 was estimated to cover 2,000 square miles and to weigh 

 42,850,000,000 tons; another swarm of similar or greater size 

 was seen on the day following. In 1868 cockchafers were so 

 abundant in Saxony that a reward was offered for them, and 



Fig. 45. A deep sea fish. 

 For explanation of the figure see p. xii. 



1,500 tons, representing about 1,500,000,000 were destroyed. 

 The most recent estimate of the total number of kinds of true 

 insects already known is 640,920, and this number is being in- 

 creased at the rate of about 6,000 every year. Large as it is it 

 is believed to represent only about one-tenth of the real total. 

 Of the more important groups the moths and butterflies num- 

 ber 205,000, the butterflies alone 50,000; the beetles number 

 202,400 (including 500 strepsipterans) ; the bees, wasps, etc., 

 number 91,000, the true flies 45,000, the dragon-flies and more or 

 less similar types 25,000, and the grasshoppers, crickets and their 

 allies 20,500. Besides the true insects there are 25,000 spiders, 

 mites, etc. 



