Cll. PRESIDENT S ADDRESS. 



individuals, all moving together and actuated by a common 

 impulse. In many cases, however, they doubtless eventually 

 return to their nest, but while on their expedition they clear off 

 everything eatable that they meet with. Some sorts will enter a 

 house and perform valuable service in destroying or putting to 

 flight all vermin, insect or otherwise, that it contains. 



GENERAL CONCLUSIONS. 



There are numerous records of insect migration, in which 

 insects of various species and of different Orders seem moved by 

 a common impulse to migrate together. Besides the cases I 

 have incidentally mentioned, I will only refer to one, in which 

 Walker notes that, after leaving Tunis in April, 1873, he sailed 

 along the Malta Channel and on to Italy for four or five days 

 through many miles of sea, on which were floating " large 

 brown butterflies, moths of all sizes, and dragon flies, evidently 

 just dead, as they had apparently not been long in the water." 



I can hardly think that these had been merely blown out to 

 sea. Butterflies and the weaker moths in a wind go, as a rule, 

 right down into the herbage, and are very safe, though the 

 stronger flying ones will often fly in numbers on a warm, though 

 very windy, night, and appear not to be in the least incommoded 

 by its violence ; at least, such is my experience in this country, 

 and it would require some special and simultaneous movement, 

 such as a migration, to gather together any large quantity of 

 insects, which must be caught by the wind before they have 

 time to hide themselves. The most extraordinary part of this, 

 and of other records similar in this respect, is the extremely mixed 

 character of the mass of insects, which suggests that different 

 species were overcome by a migratory impulse at the same time 

 and started together. As this is no isolated case, it would 

 appear that migration is, sometimes at least, caused by some 

 external condition which acts upon many different sorts of 

 insects in the same manner and produces the same kind of 



