Gathered in compact masses, like companies of soldiery preparing for a foray, hundreds of aphides were seen, busily feeding, all over the flowers. There were old and young, not an indiscriminate mingling of ages and sizes, but an orderly arrangement of families, each family preceded by its own appropriate head. First came the very young of each family, only to be followed by those that were older, leaving the oldest of all to lead up the rear.
BLOSSOM OF CUCURBITA.
Mother-Aphis and Her Army of Children on Tube.
Here, it was apparent, was a most wonderful manifestation of intelligent design. The newly-born, needing the mother’s earliest attention, were in closest proximity, while the almost mature were the farthest removed from her essential presence.
All this seemed to indicate the dearest relationship subsisting between mother and offspring, but judging from outward appearances, little, if any, love existed. It is true that maternal instinct, which is seldom so far gone as to shut its ears to the beseechings of suffering offspring for food, was far from being absent. Instances of its presence were momentarily noted.
But a stimulus seemed, in some cases, quite necessary to its manifestation. There were times when the honey-glands acted without any provocation. It was only, however, when the very tender were a-hungry, that pressure was brought to bear upon the mothers. A few gentle reminders served to arouse them from the apathetic indifference which possessed them. The antennæ of the young were the means employed for this purpose. Two or three caresses almost immediately brought a discharge of honey. Again and again was the process observed, and always with the same invariable result.
Never for a longer period than two days were the very young dependent upon this manner of feeding, for their digestive organs were too weak and delicate to assimilate earlier, without injury, the powerful juices of the food-plant.
But what of the older offspring? That they were far from being disregarded by parental provision, subsequent developments only too plainly showed. The excretion, though less urgent in their case than in that of the very young, was quite as indispensable. Were it not so, what reason can be assigned for their very strict adherence to the course over which the maternal head had already passed in feeding?
From what has been said, there can be no doubt that the newly-born aphis derives material advantage from the excretion. But as the supply is clearly above the requirements, why the excess? It is evident nature does not need it as a kind of compensation for losses sustained through aphides. Then what purpose does it serve? It becomes in part the pabulum of the stronger of the young, and this it accomplishes by mixing with the natural juices of the plant, thereby rendering them fit for use.
To serve as food for the young is then the primary object of aphis-excretion. That a secondary purpose, namely, the preservation of the species, is also subserved, there can be no question. How this is effected, it shall now be my endeavor to show.