Page:Popular Science Monthly Volume 50.djvu/117

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105
EVOLUTION OF INSECT INSTINCT.

tion in America and England, are found to be very useful in making the farmer independent of the scarcity or the exactions of laborers.—Translated for the Popular Science Monthly from the Revue des Deux Mondes.

 

EVOLUTION OF INSECT INSTINCT.
By M. CH. PERTON.

I WAS a witness in 1887 of a combat between a halictus bee and its sphœcode parasite, a "cuckoo bee," which took place in the open air, outside of the nest. The nests of the Halictus malachurus (Kirby), which are found excavated in the compact soil of garden walks, are narrower at the entrance than below, and here the sentinel bee closes access with its head.

The sphœcode, Sphœcodus hispanicus (Wesmäel), twice as large as its victims, had to enlarge this entrance to effect its passage. I saw it cut up the sentinel, whose quarters came out with the digging. Very near, a halictus was assisting a dying sister whose pollen-loaded feet were still moving. She had without doubt been killed by the sphœcode. Another harvester still survived, and attacked the parasite, biting its legs and wings. The bandit, obliged to stop its task frequently, established itself near the nest and tried to seize the enemy with its sharp mandibles. The halictus at last threw itself upon him, and the two were locked in combat. In an instant the halictus was no more.

The sphœcode labored for nearly four hours to open a passage, and would perhaps have succeeded if I had not judged it prudent to capture it. It had worked till dark without having advanced more than an eighth of an inch.

Besides the deductions which other authors have drawn from the observation of insects under similar conditions to these, I found a no less important feature toward the study of instinct in the apparent development at the same time with sociability of a courage which impels the individual to devotion of itself to the common cause. The persistent struggle which my halictus maintained is, I believe, unexampled in the annals of other Hymenoptera than ants, wasps, honeybees, and bumblebees. It was not a rush of a moment upon the thief, or a struggle in a narrow corridor where escape was impossible after the fight had begun; but it was a foot-to-foot battle that lasted nearly a quarter of an hour, in the open field, where the halictus could run away at any moment. The assault was made vigorously, of determined purpose, the contestants fighting in close embrace, and ended in the death of one of them.