RECREATIVE NATURAL HISTORY. 



81 



1 1 K A T I V K >. V TURAL HISTORY. 



CADDIS WORMS AND FLIES. 



AMONGST tho almost endless nnraber of objeota of interest 

 whii-h meet tho eye of tho searcher after brook and r-vcr treasure* 

 1 to reward his investigations more ricniy, or 

 i.pi-M up a wi.l.T ti. 1.1 fur ntndy and roflootion, than the genus of 

 torous iiiHoi'trt (1'hryyanea), to which tho so-cal led caddis- 

 .>ngs. A vast number of species have been described by 

 n inhabiting the rivers and brooks of England. Some 

 . families of insects are comparatively local, whilst others 

 to bo common wherever suitable conditions for their sus- 

 tenance and support 

 are met with. Not 

 do tho perfect 

 ! or Hi.-* of 

 tiiflVrent species vary 

 in colour, tint, etc., 

 but tho larvae, who 

 are accomplished 

 builders in their way, 

 sulopt a stylo of archi- 

 . !-o in accordance 

 with the customs of 

 the family to which 

 the constructor be- 

 longs. P.fluviacornis, 

 for example, from the 

 moment ho quits the 

 egg dropped by tho 

 parent fly to the still 

 deeps of the brook 

 pool, turns his atten- 

 tion to the collection 

 of tiny fresh-water 

 shells and minute 

 particles of shell-like 

 substances. These, 

 by a process allied to 

 that by which the 

 silkworm forms its 

 cocoon, are, so to 

 speak, spun together. 

 The glutinous fila- 

 ments of web, as 

 they are given off by 

 the insect, adapt 

 themselves to every 

 inequality of the sub- 

 stance to bo secured 

 at the point intended 

 to bo next the cham- 

 ber or tube, in which, 

 when smoothly and 

 evenly lined, the in- 

 dustrious and deft 

 worm will find an 

 abiding place. Shell 

 after shell and par- 

 ticle after particle are 

 thus added step by 



step to the structure, and as the caddis-worm grows so he increases 

 the bulk of his building materials, turning them with his ready 

 claws until they are in a position to suit his requirements. But 

 whilst wo admire his constructive talent and skilful selection, 

 truth compels us to state that P. fluviacornis is most dishonest 

 and unscrupulous in his building operations. What should we 

 say of a powerful potentate who, to build for himself a splendid 

 mansion, seized on the dwelling-houses of other people, carried 

 them off bodily, turned them upside down with tho inhabitants 

 in them, and then cemented one on the other until the tyrant's 

 stronghold was complete ? Such conduct, although highly repre- 

 hensive in the potentate, is most interesting and curious in a 

 caddis-worm, who is perfectly indifferent as to whether tho 

 freshwater mollusk fixed on for building purposes is in his castle 

 or not. If he is, he simply has to travel from place to place at 

 the will of his captor ; if not, the empty shell is taken immediate 

 possession o2. just as any other stray substance would be. 



136 N.I:. 



Caddis-worms kept in a state of confinement, and deprived of 

 the materials which their iimtinct teaches them to one, will, 

 without hesitation, employ such substances a* may be placed 

 before them. Some curious and interesting result* hare fol- 

 lowed experiment* tried on the building power* of the caddis- 

 worm. One specimen was, we are informed, furnished with 

 particles of clear, transparent glass, and, a* this wa* the only 

 substance to be obtained, he in a short time constructed hi* 

 dwelling tube of it. Through the transparent case thus formed 

 every movement of the worm could be closely observed, and at 

 length, on tho completion of the tiny coat of crystal armour, 

 tho wearer was, with other worms differently chid, placed in 



an aquarium with a 

 number of hungry an<* 

 inquisitive stickle- 

 backs, who at once 

 made an attack on 

 the plump, succulent- 

 looking morsel just 

 fallen amongst them. 

 Like a set of pirates, 

 they dashed at the 

 coveted prize, but, to 

 their confusion, dis- 

 covered that instead 

 of an unarmed and 

 easily subdued victim 

 they had run their 

 stems against a for- 

 midable armour-clad, 

 bristling with spikes, 

 and armed at all 

 points. So the pigmy 

 fleet backed astern, 

 and then sheered off 

 in consternation and 

 disgust, to seek more 

 profitable cruising- 

 gronnds. Coloured 

 beads, fragments of 

 stained glass, par- 

 ticles of pearl shells, 

 etc., are by the 

 caddis-worm, when 

 restricted in the 

 matter of building 

 material, worked up 

 into tubes, or caddis 

 houses, of the most 

 curious and pleasing 

 character in fact, 

 they become, when 

 vacated by the worm, 

 natural history speci- 

 mens which most 

 persons desire to 

 possess. Figs. 1, 2 in 

 the annexed illustra- 

 tion represent speci- 

 mens of P. fluvia- 

 cornis which have 



made use of materials of their own selection for the construc- 

 tion of their dwellings. 



Then we have another noteworthy member of the caddis 

 family in P. rombira, who may bo viewed in the light of a 

 carpenter caddis. Sticks, fraarments of bark, and strong 

 splinters of wood, are his favourite materials. These he cleverly 

 joins together, parallel to each other, forming a kind of Lili- 

 putian fagot in which to dwell. Hence it is that the term 

 fagot-worm has not unfrequently been applied to the whole 

 caddis family. Fig. 3 represents one of these Liliputian log- 

 houses. Then, again, we find a most eccentric worker, 

 whose tribe confine themselves entirely to the use of sharp 

 thorn-like spines of river-side grass for the construction of 

 their strongholds. These pointed and needle-like bars they 

 lay transversely on each other, row after row and tier after 

 tier, in such a way that, as the cavity in the centre is made even 

 and comfortable to reside in, all the points are caused to pro- 



