2G8 THE BUTTERFLY VIVARIUM. 



thing like the action of mowing; and on being 

 examined occasionally, many captures will he found 

 to have taken place ; the greatest portion of them 

 worthless, hut some prizes Avill constantly occur. 

 This operation may he carried on from dusk till 

 as late in the night as the collector chooses. It 

 also answers in broad sunlight for another class of 

 insects. 



Parks and old meadows are the best places for 

 sweeping; where the turf, having been long un- 

 disturbed, has become the permanent home of many 

 kinds of insects. 



A white sheet spread at night in a wood or 

 park, with a light upon it, will lead to plentiful 

 entomological sport; but I must dismiss this part 

 of the subject, for it would be impossible to refer to 

 half the devices invented for the capture of insects, 

 or to one-hundredth part of the insects that may be 

 so taken. Only let us consider the probable num- 

 ber of distinct species of insects already known to 

 naturalists, and it Avill be seen how hopeless it 

 would be in the confined space of this volume to 

 attempt their descriptions, except in a few cases, 

 in any other way than by sweeping generalizations. 



Decandolle pursued the following method of 

 arriving at an approximation to the total number 



