144 PRINCIPLES AND CONCLUSIONS. 



Being satisfied that the wasps distinguished colors and were disturbed 

 by a change from one to another, an endeavor was made to determine 

 more exactly the impression made by a particular color. After the red 

 paper had been over the nest for 24 hours, it was moved a foot and half 

 to the south and a blue one put in its place, in order to determine whether 

 any of the returning wasps would enter the hole in the red paper, to which 

 they were accustomed, instead of going to the real entrance through the 

 blue paper. For convenience the blue was designated as the true and the 

 red as the false entrance. In the first 10 minutes, 76 wasps went into the 

 true entrance, of which 54 first hovered over the false and about half of 

 which actually entered it and explored the grass below. Some of the lat- 

 ter, not finding the entrance here, flew away entirely, and most of those 

 that entered the true one directly did not pass above the red paper in so 

 doing. In the next 5-minute period 50 of 78 wasps went first to the false 

 entrance and afterward found the true, but after 4 hours only 15 out of 

 125 were deceived. The blue paper was then left over the nest for 48 hours, 

 when it was moved a foot and a half to the west to put it directly in the 

 line of flight and its place taken by a yellow paper, which gave a more 

 decided contrast than the blue had to the red. In the first 7 minutes 270 

 wasps returned, none of which flew straight into the true entrance, al- 

 though many passed directly over it; all hovered first over the false, 

 many of them going in and some going in and out seven or eight times, 

 so closely was the blue color associated with the idea of the nest. Three 

 minutes later, during a 5-minute period, 205 wasps first entered the false 

 and then the true hole; not one flew straight to the true, though 6 hesi- 

 tated over it and then entered without going to the false. An hour later 

 184 went into the false hole and 202 into the true one, but after 2 hours 

 more, only 76 entered the false hole to 191 for the true one, while 5 hours 

 later still only 5 out of 49 visited the false entrance. The next morning only 

 an occasional wasp entered the false hole, though one came and searched 

 in the grass after the blue paper was finally removed. 



A similar test was made with yellow paper, one of slightly darker color 

 being substituted after an exposure of 3 days. During the first period 

 nearly a third of the wasps were deceived, but during the 4 succeeding 

 ones only about one-eighth of them, while 2 hours later this dropped as 

 low as one-twentieth. The original paper was replaced and 2 days later 

 it was moved 10 inches to the south, leaving the ground about the nest 

 exposed after it had been covered with different papers for 16 days. During 

 the first 5 minutes not one flew straight to the hole, but of the 130 that 

 entered the false hole 61 finally found the true one. When the false paper 

 was moved 2 feet to the south, 107 entered the true hole and 103 the false, 

 but when the opening in the yellow paper was put 6 inches from the hole 

 and a red one placed over the latter, three or four times as many entered 

 the true hole as the false one. Somewhat similar results were obtained 

 when green paper was substituted for the red, the mistakes growing fewer 

 with increasing experience. When the green paper blew over the hole 

 and the wasps could not get in, at least 100 gathered and many settled 

 in the false hole. The green paper was taken away, exposing the ground 

 about the nest, but only 3 or 4 entered. As soon as it was replaced with 



