Don’t be afraid, spiders are friends in disguise

Press, 27 April 1984, Page 14

Don’t be afraid, spiders are friends in disguise

From time to time Australian red-back spiders arrive in New Zealand, and no doubt other countries, among ships’ cargoes. Port authorities everywhere keep a sharp eye out for them — they are prohibited immigrants and most unwelcome. Terrifying though they may be to women and children, spiders are mankind’s best friends. They make human life possible, or at any rate, bearable. Without them we would be speedily eaten out by insects. Such was the conclusion of seven British scientists who conducted a six-year survey of spiders at Bookham, Surrey, some years ago. Those arachnologists (arachne, a spider) estimated there were then more than two billion spiders in England and Wales, and that each year they ate insects weighing more than the total population of Britain. To compete with the spider’s voracity, the scientists said, a man would need to consume “a whole fat ox for breakfast; an ox and five sheep for dinner, two bullocks, eight sheep, and four hogs for supper, and, as a going-to-bed snack, about four barrels of fresh fish.” The report asserts that if it were not for the spiders’ enormous appetite we humans would have adopted or domesticated them, just as we have done with silkworms, for the sake of their super-fine thread. Spider thread is many times finer than silk, and has been woven into fabric more durable. The spider itself finds many uses

By

ARTHUR KIDSON

for this thread. All varieties weave it into bags or cocoons in which they lay their tiny round eggs — usually from 10 to 1000. The death’s head spider, which lays only half a dozen eggs disguises them as bird-droppings and conceals itself among them. Many spiders live in or on their eggnests, apparently enjoying the comfort they provide.

Others, such as the Australian trapdoor spider, use their thread to line “hidey-holes,” and to make hinged lids for them. Others roll up leaves with their thread and so make snug nests in trees. Yet another kind, the hairy water-spider, weaves its thread into a tiny diving-bell. This contains a minute air bubble which keeps the spider alive while it seeks its under-water prey. Some

surface spiders fashion their thread into miniature balloons or parachutes to disperse their young. Spider threads are made by glands in the creature’s body and emerge via four or five spinnerets on its underside. Each spinneret has many minute perforations which expel a multitude of threads, differing in kind according to the spider’s needs — sticky threads, bobbed with gum, to make spirals for the web; stouter lines to anchor it to branch or fence-line. On the under-side of the body, which includes the creature’s head, are the spider’s eight eyes, spaced in two rows immediately behind the jaws. These are single eyes, not the marvellous multiple type belonging to many insects, such as flies. Yet for all this optical battery the spider has a poor range of vision, and relies more upon the sense of touch. This enables it to avoid sticky parts when traversing its web, and decide, from a safe distance, what manner of prey has become ensnared. Small flies, too weak to struggle free, are left alone to die, and be eaten later on. Larger ones are killed or paralysed by the spider with its short pincer-like fangs, which inject a weak poison. More formidable catches, such as bees or wasps, are treated with marked respect. They are either left entirely alone, to break free if they can, or their struggles are

hampered by further threadmeshes, applied with skill and cunning. Though most spiders secrete enough poison to kill flies and other insects, very few have fangs capable of piercing the human skin. Even if they do, their venom is too weak to cause more than momentary annoyance, as a rule. So most kinds can be classed as harmless. Exceptions are the black widow spider, native to the United States and found only in North America; one or two Australian spiders; and the New Zealand katipo, found also in Australia and North Africa. This is a small glossy black fellow with a red stripe, or a row of red dots down the middle of its back. Main haunts of the katipo are under driftwood or among marram grass along sea-shores. The Maori name is said to mean “night stinger,” given because people sleeping on beaches or near them were sometimes bitten at night. Katipos, actually, are very shy creatures, and their first instinct on being disturbed is either to curl up into a ball or run away and hide. Thus they are seldom seen. And only the female, it is thought, has a poisonous bite. Spiders, in fact, are far less formidable than bees, wasps, or mosquitoes which attack in large numbers and cause frequent casualties through pain, swelling, or blistering — to say nothing of the diseases which some insects spread. Many myths based on ignorance and superstition malign the poor spider. An outstanding example is

that of the tarantula, a large hairy type generally believed to have deadly poisoning powers. In “The Story of Spiders,” Dorothy E. Shuttlesworth writes: “During medieval times, near the city of Taranto, Italy, a certain type of spider was quite common. Also common was the habit of wild dancing among the people; but eventually such dancing was forbidden by government authorities. “Apparently in an effort to be able to continue their frenzied dances, some natives claimed they had been bitten by this kind of spider and the only cure was a style of music to which they could dance in an uncontrolled fever of excitement.

“The music became known as a ‘tarantella’ and the spider was christened with the name tarantula. Actually it was a large wolf spider, belonging to the genus Lycosa. In recent years tests have been made as to the results of its bite, and no ill effects worthy of notice developed.” The quaint nuptual rites of spiders are well authenticated, and it is no myth that either during or after their honeymoon the female devours her mate, who thus serves as both bridegroom and weddingbreakfast. Yet these murderous wives make soft-hearted mothers, who will cheerfully carry a mass of unlovable yongsters on their backs.

Should one female meet and fight another (as often happens) the young quickly scuttle off, returning after the donnybrook to climb up the legs of whichever female happens to remain alive and uneaten. Male spiders, though brightercoloured, are very much smaller than their mates, which no doubt accounts for their disrespectful treatment. Compared with a sixfoot man, said the Surrey scientists, your small garden spider would have a wife 80 feet high, and weighing 90 tons.' He woos this cutie with artful posture and bizarre dance, little suspecting the fate that lies ahead. The Arachnida as a class thrive

in almost every climate and are extremely varied and widespread. There are spiders that live underground, others that nest in trees, spiders that catch fish with net and line: giant spiders in South America which snare and eat small birds. The class includes ticks, mites (one kind lives in cheese, another in ponds) and scorpions. As every schoolboy learns, and promptly forgets, the spider is not an insect. Insects have six legs. The spider has eight. It has a different bodystructure and a different lifecycle. Many insects become pests; but unlike those, the spider remains a true, though unloved, friend of man.