46 



BIRDS IN THEIR RELATIONS TO MAN. 



AN APHID, MAGNIFIED, AXI) ITS ECHJS ABOUT BVDS 



third generation. All of these early broods are what are 

 called parthenogenetic females, giving birth to living young 

 without the presence of any males. Many of these plant-lice 

 are provided with wings, but the majority are wingless. This 

 process of reproduction is continued throughout the warm 



season, but on the ap- 

 proach of cold weather 

 a true sexual genera- 

 tion is produced, the 

 males of which may be 

 either winged or wing- 

 less, while the females 

 are always wingless. 

 By union of these two 

 fornjs the true winter 

 eggs are produced : the 

 eggs are generally deposited upon the branches of trees or 

 other .plants ; they pass through the winter and in spring 

 hatch into stem-mothers which renew the cycle of existence. 

 Many of the smaller birds, such as the warblers, nut- 

 hatches, kinglets, and chickadees, appear to feed largely upon 

 aphides and their eggs. These insects are only rarely found 

 in the stomachs of larger birds, like the robin, cat-bird, and 

 the various thrushes. A large part of the winter food of the 

 chickadee consists of the eggs of aphides. 



The moths and butterflies form the order Lepidoptera, or 

 scaly-winged insects. Under the microscope their wings are 

 shown to be covered with minute scales which overlap one 

 another. The adults are very different from the larvae, and 

 in consequence these insects are said to undergo complete 

 transformations. The three later stages of the common cat- 

 erpillar which infests cabbages the cabbage-worm are rep- 

 resented in the picture herewith. The female butterflies 

 deposit their pale greenish-yellow eggs, singly or in clusters, 

 on the leaves ; the larvae soon hatch and feed upon the sur- 



