238 THE entomologist's record. 



identical with, those infesting the sycamore and other trees." It was 

 stated at the time that the aphides had evidently only been recently 

 deposited, because, although agglutinated together in masses, very 

 many of them showed signs of vitality. The day previous to that on 

 which they were found had been very calm, but the weather had 

 changed in the night, when it became windy, and it was supposed at 

 the time that, although probably the greater part of the number com- 

 posing the flight reached the shore, yet, the rear rank was blown back 

 by the wind into the sea. It is equally probable that the aphides 

 came from the land, and were deposited by the wind in the sea, instead 

 of on green fields or in orchards, and that the tide afterwards washed 

 up and deposited the dead bodies. It is most difficult to determine 

 whether such a flight as this is composed of would-be emigrants or 

 immigrants. 



Although these general migrations appear to be involuntary, and 

 the aphides are, during their progress, the sport of the wind, which 

 may deposit them in green fields or in the sea, the autumnal migra- 

 tion to another food- plant, when the supply of sap provided by its 

 summer pabulum begins to fail, is far from being so. In this case 

 the movement is due to a definite cause, and not only do the insects 

 provide themselves with food for a longer period in autumn, but they 

 select a home where the sexed forms (the development of which almost 

 immediately follows this migration) find a suitable place to lay their 

 eggs. Pairing takes place almost immediately after the appearance 

 of the sexes, and the eggs are at once laid. The number of eggs laid by 

 the female is usually very small ; sometimes only one is produced, and 

 this may remain within the body of the female, the shrivelling skin of 

 the latter enveloping and forming an extra protection to the ovum. 



Nor can the migrations of certain aphides which take place at 

 the instance of ants that preserve their eggs, etc., be considered by 

 any means involuntary. Many species of aphides have a pair of little 

 tubes projecting from the upper surface of the end of the abdomen. 

 These are called honey- tubes, and from them, after secretion, is 

 poured out a sweetish liquid, termed " honey-dew." For this honey- 

 dew they are kept by ants, who not only feed on the honey-dew when 

 it is voided, but actually milk the aphides to make them part with it. 

 Some species of ants collect the eggs of certain aphides in autumn, 

 store them during the winter, carry them out and place them in 

 favourable positions for hatching during the spring, and visit the 

 aphides in order to obtain the " honey-dew " they secrete in the 

 summer. Sometimes the ants move the colony from one place to 

 another. It is quite evident that such migrations as these are governed 

 by the ants. 



There appear to be practically no records of migrating Hemiptera 

 other than the groups already noticed. Scott records that in September, 

 1875, three specimens of L'ryptacruspinguisviQYQ captured floating on a 

 piece of old sail at the entrance to the London Docks. As this is a 

 species belonging to Cape Colony, there can be no doubt that the 

 individuals in question had been introduced by shipping, as are many 

 exotic Coleoptera and Lepidoptera almost every year. Mr. Manger has 

 shown me an example of Cicada mixta, that flew on board ship 25 

 miles ofl" the coast of Ceylon, which suggests that these insects may 

 perform considerable journeys from their native place, although no 

 systematic observations appear to have been made thereon. 



