484 HOMES WITHOUT HANDS. 



One of the most curious points in the construction of this nest 

 is the manner in which it is suspended to the branch. As is 

 shown in the illustration, the combs are comparatively narrow at 

 the point of attachment, and gradually increase in width, so that 

 their weight, when filled with the young brood, must be consider- 

 able, and the strain on the upper part of the comb very great. 

 The manner in which the insect has met this difficulty is really 

 wonderful. It has not made the upper part of the comb to con- 

 sist of a solid mass, as is the case with the clay nest which has 

 just been described, but has utilized almost every portion of the 

 comb from the top to the bottom. But, in order to obtain the 

 needful strength, the upper part is constructed after a manner 

 that is widely different from that which prevails upon the lower 

 and wider portion of the comb. 



If one of the combs were broken across, the lower half would 

 much resemble, except in color, the nest of an ordinary wasp, ex- 

 cept that the cells are smaller, and the material stronger ; but to- 

 ward the top the partitions between the cells become thicker, and, 

 in consequence, the cells are fewer. This increased strength is 

 chiefly found in the partitions which run perpendicularly, and 

 which are so thick that the hexagonal form of the cells becomes 

 obscured, the great object being, not the exact shape of the cells, 

 but their ability to bear the weight of the comb below. 



The general effect of this modification can be easily imitated by 

 taking an oblong piece of linen, rounding the corners, and plait- 

 ing one end, just as ladies gather in the upper part of an apron. 

 The longitudinal folds will then represent the perpendicular par- 

 titions of the cells, and will show how strength is gained without 

 needless expenditure of material. The strengthened partitions do 

 not run quite perpendicularly, but are slightly irregular, just as 

 would be the case with the folds of the linen if it were fastened to 

 a branch by the plaited end, and suffered to hang loosely. 



The history of Social Insects would be incomplete without the 

 mention of several British insects, which are plentiful enough, but 

 which are scarcely known as well as they deserve. These are 

 the creatures which are popularly known as Carder Bees, be- 

 cause they prepare the materials for their nest in a manner simi. 

 lar to that which is employed in carding cotton wool or heckling 

 flax. 



Several species of Carder Bee are known, all belonging to that 



