Collecting Insects 31 



jection. Why, one pair of gypsy moths, if left 

 alone, under favorable conditions, can produce 

 enough caterpillars in eight years to destroy every 

 green leaf in the United States; the Kaiser, the 

 Allies and all the guns, aeroplanes and submarines 

 could not possibly do as much damage as one pair 

 of gypsy moths and their children. 



Suppose there were no birds, and the little bug 

 called the hop aphis, which infests the hop vine, 

 were left alone and unmolested. After a careful 

 calculation, one naturalist tells us, and we have no 

 reason to doubt what he says, that a pair of these 

 little hop bugs would breed so fast that in less 

 than a year there would be six sextil lions, 6,000,- 

 000,000,000,000,000,000 children, grandchildren, 

 great-grandchildren and great-great-grandchil- 

 dren, etc., all sucking the juice out of the hop vines. 

 This nmiiber is too big for us to get the proper 

 perspective view of it, unless we put it another 

 way, and a Mr. Forbush has done this for us. He 

 has figured it out about this way: If you place 

 these little bugs, ten of them to an inch, on a 

 straight line, then shoot the line of them up into 

 the sky, it will reach so far into space that, should 

 the last little aphis on the line flash a light as big as 



