32 



It appears that there are, however, exceptions to this general rule. In the case of the 

 grain aphis, Dr. Fitch says that he has watched it the year round so closely that he is per- 

 fectly assured that no eggs were laid and no males produced, and he further states that 

 in the autumn the mature lice continued to produce their young ones until they and their 

 young became congealed upon the leaves of the young grain by the advancing cold of the 

 season, and in this state they were buried beneath the snows of winter and with the warmth 

 of the ensuing spring they were thawed and returned to life again Professor Cyrus Thomas 

 also found living lice upon young fall wheat in South Illinois in the middle o! winter, and 

 after much sleet and rain had fallen. Even so far north as Connecticut, Prof Verral found 

 numbers of wholly plant lice of all sizes on the bransh of an apple tree so late in the year as 

 December 11th, and this after two snow-storms and many cold rains and freezing nights. 

 Indeed those who cultivate plants in their houses or otherwise under glass during the winter, 

 will ot require much further evidence than their own experience to convince them that plant- 

 lice, tiny, tender looking, and juicy as they are, are endued with such perennial vitality and 

 hardihood as to require great watchfulness and frequent use of remedies for their destruc- 

 tion in order to keep them within due limits. 



In figure 4 we give a highly magnified view of 

 the apple aphis, aphis mali, hoth in the winged and 

 wingless forms ; the hair lines along side of the 

 figures show the natural size of the insects. At the 

 tip of the abdomen is seen a little projection ; this 

 is the ovipositer or egg-laying instrument, and on 

 each side of this is another little horn-like projec- 

 tion. These latter are called the honey-tubes, and 

 through them a sweet liquid is produced which i-s 

 sometimes discharged upon the leaves of the infested 

 plant, which drying up, forms a sweet glutinous 

 ■" substance known under the name of honey dew. 



Fig. 4. In olden times the origin of this honey dew was 



shrouded in mystery, and many theories were advanced by sage ])hilosophers to account for 

 the strange phenomenon. Pliny, the great Roman naturalist, hesitates whether to call this 

 honey dew, the sweat of the heavens, the saliva of the stars, or a liquid produced by the 

 purgation of the air. Thanks to the careful observatiiins of entomologists, philosopners have 

 no longer any rea.son to puzzle themselves as to its origin. 



In this connection another strange feature deserves explanation. Most attentive 

 observers will have noticed that where trees or plants in the open ground are infested by 

 plant lice, they are also much frequented by ants who are busy running up and down the 

 trunk or stem the whole day long. This association of the insects has led some to sup- 

 pose that the aphides are in some way produced from the ants, and we have heard of various 

 ingenious devices being resorted to, to prevent the ants from ascending the trees, under the 

 idea that in this manner the aphis might be in some njeasure got rid of A slight examina- 

 tion will suffice to show the fallacy of this view, and reveal the real objects the ants have in 

 their visits. It is a well established fact, as most housewives know to their cost, that ants 

 arc very fond of sweet things. Examine closely one of the groups of plant lice which are 

 being visited by the ants and jou will see one or more ants walking about among them ; 

 applying a magnifying lensc to the group, and you will presently perceive an ant drumming 

 gently on the back of a plant louse with its fliil-like antennae until it coaxes the aphis to emit 

 from its honey tubes a drop of the sugary li(juid. This the ant absorbs and parses on to an 

 Other, which is subjected to similar treatment, and soou until iiaving filled itself, it descends to 

 the earth and having regained itsne.st, discharges the sweet fluid into the mouths of the help- 

 less maggots, the larvae of the future ants, which are entirely dependent for their sustenance 

 on these industrious, working ^ants. Linneus, one of the earliest entomologists, and a most 

 careful investigator, truly observes, " the ant ascends the tree that it may milk its cows, the 

 plant lice." These hoaey tubes are shown more prominently in fig. 5, which represents a 

 wingless aphis. 



