HOMING FACULTY. 223 



The field and nest flights of the bumble-hee.— Wagner (1907:51) 

 has considered the sense of direction of Bombus under the following cap- 

 tions: (1) observations on the return to the nest by running; (2) observations 

 on the field and the nest flight; (3) observations in cages; (4) homing in 

 nature. When the wings were cut off, Bombus was unable to return to the 

 nest, showing that it was not guided by a mysterious sense of direction. 

 Each flight of this bee consists of two separate acts, the field flight and the 

 return to the nest. These are impressed upon the memory and retained by 

 it in a different manner, though this holds much more fully for the nest 

 flight. The bumble-bee finds its way on the nest flight through the careful 

 inspection of a few objects in the proximity of the nest or with the aid of 

 the main points in memory. This inspection, as well as the correlated 

 impression on the memory, can result only from the position of the body 

 as taken on the return journey to the nest. The inspection of objects, 

 which leaves recollections of their features, demands a special behavior, 

 namely, a zig-zag flight near the object; objects not observed in this manner 

 are not impressed on the memory of the bee. Such a zig-zag flight continues 

 only so long as the bee can see the objects about the nest, which is within a 

 radius of a meter at most. Beyond this sphere of vision lies one of orien- 

 tation, which includes neither nest nor the small objects about it, but only 

 such large ones as can be distinguished vaguely at a distance greater than 

 10 meters. Beyond this the flight back and forth is guided by the sense of 

 direction. Even within the sphere of vision the sight of the bumble-bee 

 is incomplete in so far as it distinguishes only a few guide-points, which 

 are rather impressions of positions than of definite objects. As a conse- 

 quence, only a decreasingly small portion of the way to and from its nest 

 remains fixed in its memory, and hence the sense of direction plays an 

 important role in the field flight and the return to the nest. 



The homing of the mud-dauber wasp. — In studying the homing 

 habits of the mud-dauber (1908:215), Turner noticed that the wasp never 

 flew directly to its nest, but always alighted on a certain crack. It ascended 

 this crack to the height of the nest and then turned and walked to the 

 latter, its behavior suggesting that the crack served as a landmark. The 

 method of experiment and the nature of the evidence may be obtained from 

 the account of the first experiment: 



"The lower shade of window number one was raised halfway and the top shade as far 

 as it would go. While the wasp was out of the room all the blinds of windows number two 

 to six were closed, except the upper shade of window number four, which was raised as far 

 as possible. 



"The wasp on entering through window number one flew obliquely upwards across the 

 beam of light from window number four to the upper third of upright C. (This line of 

 flight was convex towards the east.) It then flew vertically upwards almost to the ceiling, 

 then leftward about a foot (this is a little more than the distance of the nest from upright 

 B) and examined carefully the moulding. Not finding the nest, it began flying first to the 

 right and then to the left in constantly elongating ellipses with very short minor axes. 

 All this time it was carefully examining the moulding. Occasionally the mud-dauber 

 would fly downward into the beam of light and then resume its search. In its lateral 

 flights the wasp sometimes flew as far to the east as upright D and to the west almost as 

 far as upright B. At the end of three minutes it had not found the nest, although under 

 former conditions of illumination it required only half a minute to fly from window number 

 one to the nest. 



