Jan., '04] ENTOMOLOGICAL NEWS. 7 



days they appeared only in small numbers : but, by the end of 

 the first week, the migration had begun in earnest. The larvae 

 were to be seen crawling along the paths, but always toward 

 the front of the building. Reaching the vertical wall, they 

 would climb upward until turned from this direction by a 

 projecting course of brick or a window ledge. Anything of 

 this sort, having a horizontal under surface exposed, seemed 

 inviting to the larvae, and many secured themselves for pupa- 

 tion in such situations. 



It soon appeared, however, that the front of the building 

 was not equally favored by the larvae at all times. In the early 

 forenoon the eastern end attracted them, and in the afternoon 

 the slanting rays of the sun led a few late wanderers around 

 the corner to the western wall. Most of these wanderers, how- 

 ever, ultimately returned to the front of the building. The 

 few which pupated on the end wall chose brightly lighted 

 situations, either on white-painted woodwork or directly against 

 the vertical surface of a brick. 



On the front of the building, at. noon of a clear day, the 

 heat and light were intense, and the larvae observed there at 

 such times were seen to seek the deep shade of the water- 

 conductors in the angles of the basement wall. At other times, 

 when the conditions were not so extreme, they suspended 

 themselves in the broad daylight. Finding available situa- 

 tions on both bricks and woodwork, each larva appeared to 

 make its choice with reference to the temperature of the air 

 near the wall and the amount of sunshine. 



No larvae or pupae were found upon the north wall at any 

 time during the whole period. This may be largely due, of 

 course, to the fact that this was the aspect of the building 

 most distant from the elm trees. 



Two or three larvae sought the green fence, and pupated in 

 the partly-shaded angles of that structure. I did not see these 

 until pupation had been accomplished. 



III. COLORS OF THE PUP.E. The experiments reported by 

 \Vood i iS67), Poulton (1890) and others, showing that the 

 colors of certain pupae are determined by the colors of neigh- 

 boring objects, are well known. Poulton has further shown 



