120 WOKK AT HOME AND IN THE FIELD 



But the degree of humidity is a point not so easily settled, and 

 so variable are the experiences and opinions of different entomo- 

 logists that it is difficult to advise a beginner on the subject. The 

 fact that some strongly advise a perennial dampness, while others 

 recommend no attempt at the application of water, would seem 

 to show that there are probably important points to be urged on 

 both sides. 



Nothing can be better than a very careful observation of pupae 

 in their natural conditions. When engaged in pupa digging you 

 will observe that the larger number are to be found on the east and 

 north sides of trees where the soil is protected from the heaviest 

 rains ; on the other hand a good many are certainly found in very 

 moist and sometimes even in wet situations. 



Particular notice should be taken of such experiences, making 

 every allowance for the exceptions that prove the rule, and then let 

 the natural conditions be maintained in your nurseries at home. 

 To carry this out two pupa boxes should be kept, one for those 

 species that seem to require dry situations, and the other for the 

 species that apparently do best with moist surroundings. 



But when it is desired to maintain the pupae in a moist condi- 

 tion, great care must be taken not to allow any accumulation of 

 stagnant water. The box we have described, with its bottom of 

 perforated zinc, is well adapted for this purpose. Let it stand on 

 a couple of strips of wood, so that any excess of moisture may 

 readily drain through. The perforated bottom will also allow of a 

 free circulation of air, thus securing the ventilation that is de- 

 sirable in all boxes, whether wet or dry. 



If you have any insects that have pupated within moist stems, 

 they should be kept in a moist condition till they emerge. The 

 simplest way of doing this is to support the stems in a layer of 

 wetted but well-drained silver sand. 



Forcing may be resorted to when it is required to obtain the 

 imagines for early setting in order to get them in the cabinet before 

 the busy season begins. The method is simple. Place the pupa 

 box on a shelf in a room where a fire is kept every day. By this 

 means you may get all your specimens out within a few weeks, 

 even when you start the forcing at the beginning or middle of the 

 winter. If, however, you require the imagines for breeding, vou 

 must be careful that the eggs are not laid long before the buds of' 

 the necessary food plants are due. 



When you are expecting the appearance of perfect insects, the 



