[Illustration: The insect seen from above.]
“Among the fish that at this early season of the year (February) resort
to the waters of York River, in Virginia, the Alewife, the Oldwife,
called also the Bay Alewife, arrives in very considerable shoals, and
in some seasons their number is almost incredible. They are fully of
the size of a large herring, and are principally distinguished from the
herring by a bay or red spot, above the gill-fin. They are, when caught
from March to May, full-roed and fat, and at least as good a fish for
the table as the herring.
“In this season, each of these Alewifes carries in her mouth an insect
about two inches long, hanging with its back downwards, and firmly
holding itself by its fourteen legs to the palate.
“It is with difficulty it can be separated, and never, perhaps, without
injury to the jaws of the fish. The fishermen, therefore, consider
the insect as essential to the life of the fish; for when it is taken
out, and the fish is again thrown into the water, he is incapable
of swimming, and soon dies. I endeavoured in numerous instances to
preserve both the insect and the fish from injury, but was always
obliged, either to destroy the one or injure the other.
“I have sometimes succeeded in taking out the insect in a brisk and
lively state. As soon as he was set free from my grasp, he immediately
scrambled nimbly back into the mouth of the fish and resumed his
position. In every instance he was disgustingly corpulent and
unpleasant to handle, and it seemed that, whether he had obtained
his post by force or favour; whether he be a traveller or constant
resident, or what else may be his business where he is found, he
certainly fares sumptuously every day.
“The fish whose mouth he inhabits, comes about the same time with the
shad into the rivers of Virginia from the ocean, and continues to
travel upwards from the beginning of March to the middle of May. As
long as they are caught on their passage up the river, they are found
fat and fall of roe. Every fish which I saw had the Oniscus in his
mouth, and I was assured, not only by the more ignorant fishermen, but
by a very intelligent man who came down now and then to divert himself
with fishing, that in forty years’ observation he had never seen a Bay
Alewife without the louse.”
The Oniscus itself, as the author states, is not without its enemies,
many of them being caught with two or three leeches attached to their
body, and adhering so closely that their removal cost them their heads.