RELATIONS Ol : AXTS TO OTHER INSECTS. 



343 



aphids. If the latter are too long neglected, they discharge the honey- 

 dew on the leaves, where the returning ants find and collect it, before 

 they approach the insects by which it was voided. But if the ants 

 visit the aphids assiduously, the latter seem to comply with their desires 

 by hastening the moment of evacuation. This is indicated by the 

 diameter of the exuded droplet ; and at 

 such times they do not eject the ant- 

 manna to a distance, but, so to speak, 

 retain and hand it over to their attendants. 

 ' It sometimes happens that the ants 

 are so numerous on a particular plant that 

 they exhaust the aphids with which it 

 is covered. Under such circumstances 

 they stroke the bodies of their nurses in 

 vain and are compelled to wait till these 

 have pumped up a fresh supply of sap 

 from the stems. The aphids are by no 

 means parsimonious, and if they have any- 

 thing to give, never fail to respond to the 

 ants' solicitations. I have repeatedly seen 

 the same aphid yield several drops in suc- 

 cession to different ants that seemed very 

 eager for the syrup." 



Many aphids bear on the sides of the sixth abdominal segment a 

 pair of tubules with terminal orifices, known as cornicules, siphons or 

 nectaries. Reaumur and other earlier authors saw drops of liquid 

 exuding from these as well as from the anal opening, and from such 

 observations has come the erroneous statement that the honey-dew is 

 a secretion of the siphons instead of being merely the excrement of the 

 plant-lice. Linne, for example, says of these insects : " Plerseque 

 duo cornua, postica abdominis gerunt, quibus excernent rorem melleum 

 hae formicarum vaccae ! " And although this error, which was also 

 promulgated by Buckton in his well-known " Monograph of the British 

 Aphids" ( 1881-1883 ), has been disproved by Witlaczil. Biisgen, Kolbe, 

 Forel, Mordwilko and others, we still find it tenaciously retained in 

 many popular works on ants, not to mention text-books of entomology. 

 So careful an author as Comstock, in a book intended for students 

 ("The Study of Insects," p. 157), says: "On the back of the sixth 

 abdominal segment there is, in many species, a pair of tubes, through 

 which a sweet, transparent fluid is excreted. . . . The fluid which is 

 excreted through the abdominal tubercles is the substance known as 

 honey-dew." McCook also perpetuates this old error by publishing 



FIG. 206. Earthen aphid- 

 tent built by Cremastogaster 

 lineolata on dog-wood. (Orig- 

 inal.) The round entrance is 

 in the lower rijrht-hand corner. 



