486 University of California Publications in Zoology [VOL. 11 



more complex than in the other subkingdoms (Wood, 1907). 

 Birds must, therefore, be able to distinguish readily the differ- 

 ently colored insects as well as to note quickly differences in size 

 and any motion on their part. Hence the food taken must be 

 largely the result of the reflex acts set up by the sight of food 

 and much less as the result of studying each kind of food pre- 

 sented to determine its palatability. This brings us, of course, 

 to "hunger" as one of the prime determining agents as to the 

 kind as well as the amount of food taken. 



Then, too, many insects and animals are protectively colored 

 while at rest, but let them move and they immediately become 

 conspicuous. Experiment has shown that most of the lower verte- 

 brates depend largely on the movement of their prey to apprize 

 them of its presence. A fly placed in a cage with horned lizards 

 is unnoticed until it moves. Many a protectively colored insect 

 must escape detection because it remains at rest. Let the same 

 insect move and it is instantly detected. 



Let us take a few examples in the food of the western meadow- 

 lark. Many of the snout-beetles (Otiorhynchidae) are inconspic- 

 uously colored and often so covered with dust as to be the exact 

 color of the ground. Close search often fails to disclose a grass- 

 hopper on a grass-stem or weed, so well does it blend with its 

 surroundings. The same can be said of stink-bugs. Yet all of 

 these insects are taken in large numbers by meadowlarks. The 

 explanation probably lies in this factor of movement. These 

 insects, although well concealed while at rest, are not concealed 

 when moving, but are, on the contrary, conspicuous. 



An insect outside of its own environment is also easily de- 

 tected by its enemies. A stink-bug, although inconspicuous on 

 a green plant stem, becomes conspicuous on the bare ground. 

 This again furnishes a possible reason for the large numbers of 

 these insects found in the stomachs of western meadowlarks. 



Movement and particular environment modify the value of 

 protective or concealing coloration. There may also be still other 

 factors which modify its value. Size and bright coloration must 

 add to an insect 's conspicuousness in both movement and change 

 of environment. All evidence from this investigation points to 

 the fact that although certain insects may be protectively colored, 



