In ‘Insect Transformations,’ (p. 102,) it is mentioned that the
distinguished Swedish naturalist, Baron De Geer, “discovered a female
earwig in the beginning of April under some stones, brooding over a
number of eggs, of whose safety she appeared to be not a little jealous.
In order to study her proceedings the better, he placed her in a
nurse-box, filled with fresh earth, and scattered the eggs in at random.
She was not long, however, in collecting them with all care into one
spot, carrying them one by one in her mandibles, and placing herself
over them. She never left them for a moment, sitting as assiduously as a
bird does while hatching. In about five or six weeks the grubs were
hatched, and were then of a whitish colour.”
These observations the author of ‘Insect Transformations’ has just had
an opportunity of verifying and extending, and has communicated to us
the following interesting facts:--
“About the end of March, I found an earwig brooding over her eggs in a
small cell scooped out in a garden border; and in order to observe her
proceedings I removed the eggs into my study, placing them upon fresh
earth under a bell glass. The careful mother soon scooped out a fresh
cell, and collected the scattered eggs with great care to the little
nest, placing herself over them, not so much, as it afterwards appeared,
to keep them warm as to prevent too rapid evaporation of their moisture.
When the earth began to dry up, she dug the cell gradually deeper, till
at length she got almost out of view; and whenever the interior became
too dry, she withdrew the eggs from the cell altogether, and placed them
round the rim of the glass where some of the evaporated moisture had
condensed. Upon observing this, I dropped some water into the abandoned
cell, and the mother soon afterwards replaced her eggs there. When the
water which had dropped had nearly evaporated, I moistened the outside
of the earth opposite the bottom of the cell; and the mother perceiving
this, actually dug a gallery right through to the spot where she found
the best supply of moisture. Having neglected to moisten the earth for
some days, it again became dry, and there was none even round the rim of
the glass as before. Under these circumstances, the mother earwig found
a little remaining moisture quite under the clod of earth upon the board
of the mantel-piece, and thither she forthwith carried her eggs.
“Her subsequent proceedings were not less interesting; for though I
carefully moistened the earth every day, she regularly changed the
situation of the eggs morning and evening, placing them in the original
cell at night, and on the board under the clod during the day; as if she
understood the evaporation to be so great when the sun was up that her
eggs might be left too dry before night.
“I regret to add, that during my absence the glass had been moved, and
the mother escaped, having carried away all her eggs but one or two,
which soon shrivelled up and will of course prove abortive.”
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