190 MR. C. B. HARDENBURG 



outdoors. For such caterpillars as are found iu more 

 shady situations the light can be diminished by putting 

 the breeding cage farther from the windo\N' or, if neces- 

 sary, covering the cage Avith a cloth or paper. We can 

 easily subdue the light but Ave cannot add to it. Thus 

 the breeding cage should have two sides made of glass. 

 We have found that the cages made of wire gauze on all 

 four sides are in many cases too dark for larvae Avhich 

 are surface feeders; the caterpillars do not seem to 

 thrive and are retarded in their development. This does 

 not matter so much if w^e are merely desirous to obtain 

 the various instars of the caterpillar, as long as it lives 

 and goes through its transformations, but it is a great 

 drawback if at the same time we wish to secure data 

 on the length of its various instars, its behaviour, etc. 



As to moisture : sufficient moisture must be supplied 

 to keep the food fresh. This is most easily done by 

 putting the twig of the food-plant into a small tube con- 

 taining water. But the space left between the twig and 

 the edges of the vial must be lilled up with cotton wool 

 to prevent small larvae from drojjping down or crawling 

 down the stem into the water. A wide bottomed small 

 bottle is preferable to a narrow vial as in the latter case 

 the weight of the larvae on the leaves is apt to disturb 

 the balance and make the vial fall on its side, spilling the 

 water and wetting the food and the larvae. 



Cleanliness is of prime importance. No frass or 

 droppings must be allowed to accumulate on the bottom 

 of the jar. When the sides and bottom of the breeding 

 cage are kept clean, the contents can be better observed 

 while any cast skins can be readily noticed. Further, 

 del)ris and excreta soon go mouldy and this condition 

 renders the air unhealthy for the larva? and promotes 

 disease. This may sound so self-evident as not to be 

 worthy of menticm but it is surprising how often we 

 have found this simple precaution, which is the cause of 

 the failure of so many breeding experiments, overlooked. 



Another important point in connection with this 

 breeding is clo.se attention and careful inspection. The 



