310 



♦ KNOW^LEDGE ♦ 



[August 2, 1886. 



under the general name clothes motli, i.e., as attacking 

 some kind or other of animal fabric. They are T. pelllo- 

 nella, biseUiclla, tapeizella, and rustkella. As the habits of 

 these are somewhat different, it will be necessary to treat of 

 the species separatelj*. 



And first as to T. peUionella. This is a little creature 

 about half an inch in expanse of wings. Its fore wings are 

 of a shining gi-eyish yellow colour, with three indistinct 

 brownish sjjots in the middle, and the hind wings are whitish 

 grey. It is an abundant species in houses, and may be found 

 at any time between January and October, though most 

 abundantly in the early summer months. Of course the 

 moth itself is innocent enough ; it is in the larval state that 

 it does all the damage to clothes, furs, feathers, <fcc. The 

 larva is a tiny caterpillar, dull whitish, with a reddish brown 

 head. It is remarkable as being the only one of our four 

 clothes moths that makes a tunic or moveable case for itself, 

 protected by which it roams in search of congenial food over 

 our stores of unused and undisturbed garments. Muffs, 

 tippets, and other fur garments it particularly delights in, 

 and many are the valuable furs it has altogether ruined, not 

 so much by the actual quantity of hair devoured, as by the 

 amount it has snipped off and wasted. 



The case is most ingeniously constructed ; it is made of 

 two m.aterials : an outer layer of fragments of the fabrics 

 that have foi-med the little creature's food, and an inner 

 layer of silk, which forms a beautifully soft and smooth 

 lining, and is secretetl by the caterpillar itself in a manner 

 similar to that in which the silkworm forms its well-known 

 cocoons. It is neaily cylindrical in form, hut of slightly 

 larger diameter across the middle, and a little flattened 

 above, and is open at both ends ; when crawling or feeding, 

 the little inhabitant thrusts out of one end its head and the 

 three segments of the body behind it, these being the ones 

 that carry the three pairs of legs by which locomotion is 

 efiected. As it proceeds on its way it keeps this anterior 

 |iart of the body exserted, and holding on to the silken 

 lining of its case by its claspers, which are situated towards 

 the other end of the body, drags its house along with it. If 

 danger menaces, it retires completely into its case. The 

 cases are of course vevy varied in appearance; from the 

 method of their construction it is manifest that their colour 

 will depend upon that of the material upon which the insect 

 has been feeding, and by judicious variations of its dietary 

 the little tailor can be induced to form cases of all conceiv- 

 able tints, or mixtures of such. 



The method employed for adapting the case to the needs 

 of the growing caterpillar is truly marvellous. It is obvious 

 that two kinds of enlargement will be necessary ; with the 

 growing stattire of the larva the case will need elongation, 

 but it will require an increase in circumference as well ; and 

 though the meeting of the former demand presents no 

 difficulty nor necessitates the exercise of much sagacity in 

 the device of a method, the latter might well be the suliject 

 of considerable perplexity, and one is scarcely prepared for 

 the extreme ingenuity manifested by the little creature in 

 meeting the diflaculty. Wlien it finds its quarters becoming 

 too strait it slits up the case on one side for half its length 

 by means of its scissor -like jaws, and fills up a certain space 

 between the severed edges with the same materials as com- 

 pose the rest of the case. This done, a similar slit is made, 

 say, at the other end, and the like process gone through 

 again. Though the circumference is now increased through- 

 out, this is not the end of the operation, for the new pieces 

 having been let in only on one side the case thereby becomes a 

 little unsymmeti-ical ; therefore to restore the symmetry of 

 its form two precisely similar operations are carried out on 

 the other side, so that to comjjlete the process no less than 

 four slits have to be made — two at each end — and to be 



successively filled up with the usual materials. It would 

 appear, however, from the observations of Reaumur, that 

 the insect does not always observe the same order in making 

 these slits, but may vary the order indefinitely. 



To lengthen the case all that is necessary is to add succes- 

 sive rings of silk and woollen fibres to the ends, but even in 

 this simple operation there is a choice of methods, for the 

 addition might be made at one end only or at both ; the 

 latter device is the one adopted. First of all a ring of new 

 material is added at one end, to effect which the grub does 

 not need to leave its tunic, the whole operation being able 

 to be performed from the inside ; a layer of silk is spun out 

 in the form of a continuous thread, and then a number of 

 tiny fillets of the woollen fabric, or fur, are attached to its 

 outer surfxce by other silken threads. This done, the cater- 

 pillar, still without quitting its shelter, rapidly reverses its 

 position, bringing its head into the position previously 

 occupied by its tail ; the extreme flexibility of its body, and 

 the rather wider diameter of the case in the centre, enable 

 it to do this very quickly ; then the same addition of a ring 

 of felt is carried out at the tail end, and in this way the case 

 is elongated equally at the two ends, and what was originally 

 the middle always remains such, and therefore the oldest 

 part is always to be found in the centre and the newest at 

 the ends. 



When the grub is full fed, it must set its house in order 

 and prepare for the helpless condition which precedes its 

 final metamorphosis. The chrysalis state is assumed inside 

 the case, the caterpillar liecoming, by throwing oft' its last 

 larval skin, a little yellow-ish brown helpless thing, similar 

 in form to the well-known chrysalis of the larger moths. 

 Now a danger has to be guarded against ; the insect has to 

 remain some weeks in this state of inactivity, and if the case 

 with its precious freight were simply left lying on the cloth 

 as usual, any moving of the latter might cause the little 

 bundle to roll off and fall no one knows whither and into one 

 knows not what perils. To guard against such a catastrophe, 

 the caterpillar, when it feels the inward promptings which 

 are prophetic of its approaching change, spins some fine 

 silken threads from the ends of the case, and attaches them 

 at their outer extremity to the cloth on which it has been 

 feeding, thus as it were casting many anchors out of both 

 bow and stern of its little boat ; its fate is in this way linked 

 with that of the larger object, and a much greater degree of 

 security is thus ensured. Very frequently, however, it 

 altogether forsakes the cloth, and chooses some retu-ed corner 

 or crevice in which to anchor its little craft. Thus all 

 through the three weeks of waiting for its wings it lies in its 

 case, like a mummy in its sarcophagus. 



At length the time arrives for the final change. The 

 chrysalis, by the aid of sundry little spines arranged in 

 transverse rows along its back, one row on each segment, 

 works itself along till it reaches the end of the case, and then 

 the imprisoned moth, bursting its chitinous covering at the 

 head, gradually extricates itself from its cerements, which it 

 leaves half projecting from the now useless sarcophagus. The 

 cast chrysalis case forms a very pretty microscopic object ; it 

 is almost transparent, slightly tinged with yellowish brown, 

 and shows distinct cases for the antenna", which cleaily 

 present slight constrictions corresponding to the multitude 

 of joints of which the organ itself was composed. It also 

 very plainly shows the hooks along the back, and those on 

 the terminal segment are seen to be the largest and most 

 powerful. On its first exclusion from the chrysalis, the 

 moth's wings are very small and soft, but after a while they 

 expand until they have reached their normal dimensions, 

 and acquired their normal consistency. 



Now the little being is ready for the fulfilment of its 

 mission, the propagation of its species. Its methods of 



