24 CHAPTER II. STRUCTURES FOR PROTECTING EGGS.-MASON-WASPS; MASON-BEES; MINING-BEES. THE provisions which are made by the different species of insects for protecting their eggs, appear in many cases to be admirably proportioned to the kind of danger and destruction to which they may be exposed. The eggs themselves, indeed, are not so liable to depredation and injury as the young brood hatched from them; for, like the seeds of plants, they are capable of withstanding greater degrees both of heat and cold than the insects which produce them. According to the experiments of Spallanzani, the eggs of frogs that had been exposed to various degrees of artificial heat, were scarcely altered in their productive powers by a temperature of 111° of Fahrenheit, but they became corrupted after 133°. He tried the same experiment upon tadpoles and frogs, and found they all died at 111°. Silk-worms died at a temperature of 108°, while their eggs did not entirely cease to be fertile till 144°. The larvæ of flesh-flies perished, while the eggs of the same species continued fertile, at about the same comparative degrees of heat as in the preceding instances. Intense cold has a still less effect upon eggs than extreme heat. Spallanzani exposed the eggs of silk-worms to an artificial cold 23° below zero, and yet, in the subsequent spring, they all produced caterpillars. Insects almost invariably die at the temperature of 14°, that is at 18° below the freezing point*. The care of insects for the pro * See Spallanzani's Tracts, by Dalyell, vol. i. tection of their eggs is not entirely directed to their preservation in the most favourable temperature for being hatched, but to secure them against the numerous enemies which would attempt their destruction, and, above all, to protect the grubs, when they are first developed, from those injuries to which they are peculiarly exposed. Their prospective contrivances for accomplishing these objects are in the highest degree curious. Most persons have more or less acquaintance with the hives of the social species of bees and wasps but little is generally known of the nests constructed by the solitary species, though in many respects these are not inferior to the others in displays of ingenuity and skill. We admire the social bees, labouring together for one common end, in the same way that we look with delight upon the great division of labour in a well-ordered manufactory. As in a cotton-mill, some attend to the carding of the raw material, some to its formation into single threads, some to the gathering these threads upon spindles, others to the union of many threads into one,—all labouring with invariable precision because they attend to a single object;-so do we view with delight and wonder the successive steps by which the hive-bees bring their beautiful work to its completion, striving, by individual efforts, to accomplish their general task, never impeding each other by useless assistance, each taking a particular department, and each knowing its own duties. We may, however, not the less admire the solitary wasp or bee, who begins and finishes every part of its destined work; just as we admire the ingenious mechanic who perfects something useful or ornamental entirely by the labour of his own hands,-whether he be the patient Chinese carver, who cuts the most elaborately decorated boxes out of a solid piece of ivory, or the C turner of Europe, who produces every variety of elegant form by the skilful application of the simplest means... Our island abounds with many varieties of solitary wasps and bees; and their nests may therefore be easily discovered by those who, in the proper seasons, are desirous of observing the peculiarities of their architecture. MASON-WASPS. In September, 1828, a common species of solitary mason-wasp (Odynerus, LATR.) was observed by us* Odynerus.-Natural size. on the east wall of a house at Lee, in Kent, very busy in excavating a hole in one of the bricks, about five feet from the ground. Whether there might not have been an accidental hole in the brick, before the wasp commenced her labours, is unknown, as she had made considerable progress in the work when first observed; but the brick was one of the hardest of the yellow sort made in this neighbourhood. The most remarkable circumstance in the process of hewing into the brick, was the care of the insect in removing to a distance the fragments which from time to time she succeeded in detaching. It did not appear to suit her design to wear down the brick, particle by particle, as the furniture-beetle (Anobium pertinax) does, in making its pin-hole galleries in old wood. Our wasp-architect, on the contrary, by means of her strong tranchant-toothed jaws, severed *J. R. Mandibles-Jaws of Mason-Wasp.-Greatly magnified. a piece usually about the bigness of a mustard-seed. It might have been supposed that these fragments Iwould have been tossed out of the hole as the work proceeded, without further concern; as the mole tosses above ground the earth which has been cleared out of its subterranean gallery. The wasp was of a different opinion; for it was possible that a heap of brick chips, at the bottom of the wall, might lead to the discovery of her nest by some of her enemies, particularly by one or other of the numerous tribe of what are called ichneumon-flies. This name is given to them, from the similarity of their habit of destroying eggs to that of the little animal which proves so formidable an enemy to the multiplication of the crocodile of Egypt. They may be also denominated cuckoo-flies, because, like that bird, they thrust their egg into the nest of another species. These flies are continually prowling about and prying into every corner, to find, by stealth, a nidus for their eggs. It might have been some such consideration as this which induced the wasp to carry off the fragments as they were successively detached, That concealment was the motive, indeed, was proved; for one of the fragments which fell out of the hole by accident, she immediately sought for at the bottom of the wall, and carried off like the rest. It was no easy matter to get out one of the fragments, as may readily be conceived, when the size of the insect is compared is the with that of the entrance, of which this exact size, as taken from the impression of a bit of dough upon the hole when finished. It was only by seizing the fragment with her jaws, and retreating backwards, that the matter could be accomplished; though, after the interior of the excavation was barely large enough to admit of her turning round, she more than once attempted to make her exit head-foremost, but always unsuccessfully. The weight of the fragments removed did not appear to impede her flight, and she generally returned to her task in about two or three minutes Within two days the excavation was completed; but it required two other days to line it with a coating of clay, to deposit the eggs, two in number, and, no doubt, to imprison a few live spiders or caterpillars, for the young when hatched,—a process which was first observed by Ray and Willughby, but which has since been frequently ascertained. In the present instance, this peculiarity was not seen; but the little architect was detected in closing up the entrance, which was formed of a layer of clay more than double the thickness of the interior lining. In November following, we hewed away the brick around this nest, and found the whole excavation was rather less than an inch in depth. Notwithstanding all the precautions of the careful parent to conceal her nest, it was found out by one of the cuckoo-flies (Tachina larvarum ?)—probably a common species very similar to the house-fly, but *Ray, Hist. Insect. 254, |