IN TOUCH WITH NATURE

Otago Daily Times, Issue 20930, 21 January 1930, Page 2

IN TOUCH WITH NATURE

WONDERFUL BASKETS OF EGGS. By J. DRUMMOND. F.L.6.. F.Z.S. In these days, observations on the venders of natural history should be highly specialised. The best of them are so. Nature’s realm is so vast that general observations disclose only the tiniest parts. The most glorious views, the most valuable knowledge, are obtained by concentration on well-chosen points, which soon open up vista after vista, in countless numbers and in boundless expansion. It is desirable to give time and patience to not merely a single group of Nature’s children, such as the birds, the insects, or the reptiles, but to a single species, such as the kiwi, the Red Admiral butterfly, or the gecko lizard. Better still, a single character, habit, organ, or anatomical peculiarity of a particular species might be taken in hand. This is the case with plants as well as with creatures. The results obtained in this way are shown by the observations of Mr E. D. Pritchard, Norman’s Hill road, Onehunga. He has specialised on the green mantis, a plentiful insect that has come under the observation of many people. He has concentrated on the mantis’s methods of laying its eggs and of making its egg-baskets. A mantis’s egg-basket may be found at any time of the year, an inconspicuous little structure, brownish or grey, about three-quarters of an inch glued to a twig, a stem, a post or a paling. One evening, about a year ago, Mr Pritchard caught a female mantis in a rhododendron bush, placed it in a box with a glass front, kept it under observation through the glass, and wisely made notes of what he saw.

After the eggs were laid on a straw in the prison, the mantis produced a white, frothy substance like whipped white of egg. With this the ’eggs were covered. It hardened and became an eggbasket of the usual type. The work was fairly long, and, presumably, tedious. When it was completed the mantis crawled slowly and unsteadily from the straw, evidently exhausted by its efforts. For 13 days afterwards, the mantis took no food. On one occasion, it held a house fly in its claws for 30 minutes, but allowed the fly to escape, Mr Pritchard believes' that the mantis’s desire to protect its precious eggs was stronger than its craving for food. It died after having been under observation for 70 days. On dissection, the egg-basket was found to contain about 70 young, partly developed, but every one dead.

Further observations on the mantis and its eggs were made by Mr Pritchard last year. He wrote on December 27: "At thlß season when the mantis may he seen in stages of development it is interesting to reflect again on the egg-basket’s marvellous architecture. It is a wonderful thing, if only on account of the construction by a slender creature of a veritable fortress for its eggs and its young.” Mr Pritchard has written again to correct statements that an egg-basket, because it has, say, 20 openings along its ridge, contains only 20 eggs. His observations show that three times that number is nearer the_ total. Repeated observations convince him that the average number of eggs in a single egg-basket is 60. This can be checked in two ways, ho explains. The most reliable way is to note the actual egg laying operations, in which a mantis tells its own story. A more convenient way is to dissect the egg-baskets carefully and to count the egg shells in it. Each egg shell lies in a depression it makes in the frothy substance of which the egg-basket is made. There are three egg shells below each opening on the ridge of the egg-basket. If there are 20 openings, there are 60 eggs. In one dissected egg-basket made in captivity, Mr Pritchard found that all the eggs had been hatched, but that, all the young were dead and were partially dried. This may have been brought about by exceptionally bright sunshine and warm temperature on a September day at a critical time in the lives of the young. A female mantis evidently has great anxiety in rearing her family. The infantile mortality is heavy. Still, her families are so large that a good margin is provided. A mantis mother seems to be like the old woman who lived in a shoe and had so many children she didn’t know what to do.

Having been taken into the mantis’s confidence in respect to some of its most intimate domestic affairs, Mr Pritchard may cement the friendship and add to the interesting information he has kindly given the public through this column. He may have something to state as to the use of spines on sheathe that temporarily cover the bodies of young mantises. It is believed that the spines are special equipments to enable the young to wriggle out of little cradles in which they are hatched. All spines point backward. The young inside the egg-baeket contract and s expand their bodies. Pressing against the egg-basket’s framework they from the openings, and, for the first time, see the wonderful outside world, utterly unlike the close, cramped place in which they were born, although it is very beautiful and cosy and comfortable.

In Europe a young mantis took 20 minutes, after it had become restless inside, to make its way out of its cradle. It still wore its sheath, bearing rough processes which pointed backward, and which had helped its wriggles. In the twinkling of an eye, when the young had its head out and its body half free on the surface of the egg-basket, the sheath was burst. At the head of the sheath there was a conical cap used, apparently, to resist friction on the way out. Two threads springing from the tail end of the body originally bound the sheath to the wall of the compartment in which the young one was hatched.

The young of New Zealand’s mantis crawl on the surface of an egg-basket as soon as they emerge. In the tropics the young of some mantises, on emerging, hang in the air upside down by two threads attached to their bodies. There they hang for hours_ or for days, until they go through their first moult. The length of a New Zealand mantis's life may be discovered by Mr Pritchard. In England, a male mantis has lived for a month, a female for three or four months. Every mantis has a cloak of invisibility, harmonising with its surroundings and Bit protection from enemies. r egg-baskets are seen much oftener than the mantises that make them.

To. demonstrate the protectiveness of mantisea’ costumes, an Italian naturalist tethered 20 green ones amongst green herbage and 20 brown ones amongst withered frass. After 17 days dll, green and brown, were alive and well. By their colours they had escaped the notice of enemies. He tethered 25 green manuses amongst brown herbage. In 11 days, every one was dead. He tethered 45 brown mantiees on green grass. At the end of 17 days only 10 were alive. Most of those that perished were taken by birds. Ants took a few of the green ones. New Zealand is a verdant country, and the wearing o’ the green is an obvious advantage to 1 the only species of mantis it possesses, a very bright green one, Orthodera ministralish, common in Australia also. It is as shockingly voracious as its relative in other countries, as skilful in constructing its egg-baskets, as disgusting in its cannibalism, and as whimsical in appearance, but it does not usually bear either of the popular names of Mantis, religiosa of Europe, the “ praying mantis,” and “the soothsayer,” probably because superstition is less rife in this country.

. The destructive house-borer, a beetle, is one of the little people. Amongst the large insect destroyers in New Zealand is the white caterpillar of the giant woodmoth, more than three inches long. It is an Australian. It came to New Zea land without invitation, in imported hardwood poles. Boring tunnels in the trunks of gum trees, it damages valuable timber. When fully developed in the caterpillar stage, the insect plugs the opening of its home with a silken wad. Then it leisurely transforms itself into a chrysalis. After V n^ A w^ e changes take place in its structure and t organs, it emerges as a large moth with chocolate-brown winas and a greyish-brown body. The females of this moth, with a wing expanse of eight inches, are the largest moths in New Zealand, The males, smaller than the females, have a wing expanse of about five inches. Next m size in New Zealand comes a native, the ghost moth, fairly plentiful judging by the numbers of specimens sect for identification. Some female ghost moths have a wing expanse of six inches. -l a ema ! e ghost moths may be identified by their large size and by their