Show B 4 A Af Ab f b y r C ka kava va rh Q Y v 11 d I t Y i I Y a y k Z L t t C t s y va A A Y s 's s Y a hS yr r yn n R y Rf f J 1 f- f if n I 4 r Sf w 3 J a it o aa t z zI fy 0 1 Y 3 y aa r I az i t t 4 a a h Y Yc r L 4 y Y aE E l a A c y I f 1 J f F rF a 0 ark 4 a 9 r r of i y I Ios r M os cs c's up ups t s t J lf l Y f y Aa Sa I It tL h L r t y 4 h ru H u us i H h 1 r t th 1 h rt k y s as I t rf j t I Ial al at t a Ea 9 i a f fa a r Z r 1 y I r ai air aih air air aia h r rt v r a z A As C s yes c R N ah ahw w s sA r ab 6 Z f A y rf r rn n a z 4 J a c n 6 f N w o tr r f fa fu fc u r ra st ia is isI I t a y 69 M Ka f MACS Kau u ud d y y Ctt gYa g a a e w o r rJ J r a pE J v x a t te as e a v a 2 lr rr ee The I Ingenious Trapdoor SpIder Prepared b bi Geographic Society D C C Service the mere mention A of spiders to most laymen aymen gives hem the creeps the Insect has been the subject of Interest Interesting interesting ing scientIfic stUdy by entomologists the spIder enthusiast sojourn sojourning Ing In the country Vt whether hether in the Unit Unit- United ed States or In any other land of tem tem- temperate climate the dawn of a late mid midsummer midsummer summer da day In a marsh meadow hoI holds s promise ot of delight It Is spider sea season season son the time when the faIry spinners are to be observed ed at their best when small dainty webs usually overlooked stand out In perfect design against the green of leaf md and grass the filmy silk glistening with Ith dew Webs webs hundreds even hundreds here of them thousands of them billow a gossamer sea In the mOl morning light l I There are arc funnel webs sheet webs hammock webs webs of shapes and finest of an all near the edge of the woods the beautiful orb webs bejeweled In theIr radiant symmetry Spiders are marvelous spInners From the many microscopic spigots at atthe atthe the tips of their heavy abdomens they conjure several se kinds or of silk with whIch to construct webs of exquisite design n and beauty They make snares for their prey sac sacs for their eggs she shel shelters tern for protection from enemies draglines for security In movement balloons for the skies and many other things for service In their varied and romantic lives Although the silken m en webs are of many different design the finery of the individual spider does not change with the passing seasons Each dies cles has Its own style of web to whIch all alI Its members adhere so long as en environment remains unaltered by geo geologic geologic logic progress Evolution of the Web Students believe the first web a 8 simple tube evolved e 01 ed from the dra drag lines used h by the spider In goIng In Inand and anel out of a hole to In the ground Its first retreat These of silk finally fin lined the nest and radiated from the entrance Stoking a against the lines victims would he be detected and seised by bv the watchful spider Uv By extending e the sheet cheet about the entrance to th the tube and bringing the latter out of the ground the spIder developed the funnel web The axis adl adlof of the web ph was shifted It ip the course of this change ch until the tube of the funnel almost and later the lower part was v as expanded Into a net These changes gIve us the ical funnel web such ns as Is spun by byth thi th common gass g spIder Angelena 11 Inside the tube of the funnel espe dally when hen this tube leads backward tangled led blades of grasses the spider still has hac protection from Its en enemies The placing of the web aho e ethe the ground and the expansion ot of the 10 Inver cr part or of It Into a sheet sed It its efficiency as ag an In insect pct snare The tube which leads away from the sheet part of a funnel web be become becomes comes come an Inconvenience when webs ebs are placed In e po pct positions above e the ground hence the sheet cheet web eb s eav cavers ers rs leave lelve It out By v spinning the sheet In e posed positions they me ate able to increase their catch or of Insects Such Cuch closely cloSE v woven 0 en sheets however offer dangerous dang to the wind Bowl and Dome Webs Spiders commonly modi f sheet cbs In two was fi S They may bring the sides of the sheet upward to produce a hammock or bowl or downward to form a dome The advantage of the bowl type Is e rosily v rioted noted by lUg our bo bowl 1 and dolly doHy spider rt It places es Its web neb well Veil be below below low the tops of small shrubs or large lare herbaceous plants and directly under the fa favorite feeding places of such In Insect insects sect sects as plant lice and leaf leat hoppers N Naturally e every ery disturbance of the twigs and leaves shakes es a shower of into the snare The dome shaped web Is better suIt suited ed cd for catching Insects rising from the ground In flight as many do about dusk or In the morning net webs haphazard tan tangles of threads of nIl all lengths are spun pun hr h that er ot of housewIves In all temperate climates the common house spider and by many other specIes Once consIdered primitive such webs now are regarded as degenerate They probably represent an evolution from I the sheet h pe altered to decrease re- re resistance re- re resistance to the wInd and to facilitate mending As fly traps they are tive and In addition usually serve I Ii i well weB for rearing the brood ot of spIder lings I i I Like human fishermen many spider species have found that a plane net of two dimensions Is not only econom I teal leal of weIght and materials but Ideal for landing a catch The rhe orb web I bunt built on this principle may be put in 10 I exposed places n Where here prey Is most i plentiful since with its open construe tion It offers little resistance to the wind vInd I Suspended from n a framework orl of I stout base lines and carefully spaced I Ito to permit freedom of mo movement ement in I spinning Its threads form a wheel like design of strength with mInimum of material The spider sits at atthe atthe I the hub ready Instantly to detect a snared victim and pounce upon it In Inthe Inthe the net snare method of catching prey the orb web Is the spiders spider's vast st word rew It if any other animals human or subhuman have equaled It orI I Although h tho most symmetrIcal web ever made by a spider Is not really perfect perte-ct according to human standards I scIentists man marvel el at the accuracy with which angles and distances are meas II Method of Construction The spider starts her geometrIcal web with perImeter lines connecting objects around a space large enough for her purpose From these lines JInes the he suspends a few threads which con converge verge erge at the center of the future web Now ow begins the process of spacIng the radII She attaches the end or of a new radius at the center and runs along alonga a spoke already laId dove don n spinnIng out th tha silk Uk for the new one as she goes When she reaches the perImeter line Ime she tales takes a fled thed number ot of steps along It the new thread ThIS process Is repeated until aU all the desired are In place placeIt It If the foundatIOn lines should chance to form a wheel Vt heel rIm accurately circular cular the distances between spokes would be equal but since the perl peri- perimeter meter met r Is usually an Irregular quad quadrangle rangle and never a circle the spacing varIes somewhat The spiral turns of sm silk which corn com complete the net are more accurately spaced spInner than the radII sInce the spIn tier ner lays down n each new turn with her touching the last one Thus the length of the forelegs and the sIze of tIle the spIder determine these dis distances Scout stepping and the use of the leg leg ruler are arc Instinctive In spiders Cven when hen Isolated from Its kind hInd from the moment of Its birth a will produce exactly the same s v web eb de design design sign as Its mother and in exactly the same ame manner Spiders constitute a large clan of some 25 described specIes Al AI though Although most abundant and dl In the 1 the they v range far Into the Arctic regions and are found almost e that earthly conditions will m sustain life up on fount Everest above abo e hIghest plant life at an elevation ele of feet spiders ha have hae e been found liv 11 Ing among the wInd and snow swept tocks Thus they are the loWest loftiest per manent Inhabitants of the earth Some spiders such ns as the trapdoor makers occupy only a restrIcted area others such fiC as our common commo house spider are round found In runny many lands and nd all 11 the continents The largest spiders fire are the cnn can tarantulas and of these the South species with Ith a bOdy 34 4 Inches long Is th the giant Its hulk bull Is more times Umes that of the smallest known spider rn In Central Centra America Is found Its clos est closest rival In size nis South America produces both the and the of spiders one ot of the latter beIng rel h barely one twenty t fifth of an Inch In len length th |