Februaky 1, 1893.] 



KNOWLEDGE. 



33 



\, 



■:\ 



Fig. 11. — Hairs of 

 larviE of (a) Drinker 

 Moth ; (b) Oak 

 Egger; very greatly 

 magnified. 



CATERPILLARS.-IV. 



r.y E. A. Butler. 

 {Continued from paije 7.) 



THE frequent handling of a hairy caterpillar naturally 

 causes some of the hairs to become detached, 

 thereby often occasioning much annoyance to the 

 operator, and the finer the hairs the more 

 disagreeable the results. These slender little 

 appendages, partly by reason of their barbed structure, 

 and partly in consequence of the minuteness of their points, 

 cling to or penetrate the skin, and are difficult to get rid 

 of; rubbing generally makes matters worse, only causing 

 the hairs to chng all the more tightly. They thus act as 

 mechanical irritants, producing a tickling and worrying 

 sensation, especially when they become attached to the 

 skin between the fingers. The caterpillars of the drinker 

 and oak egger moths (Fig. 11) are 

 perhaps the greatest sinners in this 

 respect. They are closely covered with 

 a short thick pile, which not even the 

 most careful and tender handling can 

 keep from coming off ; the little hairs 

 enter the skin, sticking in it upright, 

 but the fragments are so short that it 

 is not easy to see them, and they are 

 usually too fine to be seized between 

 the finger nails or to be extracted by 

 means of tweezers. But there are a 

 few insects whose power of annoyance 

 is far greater than this, so great in- 

 deed as to suggest the presence of 

 some poisonous principle in the hairs. 

 Amongst British insects there are two which have attained 

 this undesirable notoriety, and which, when handled, pro- 

 duce exceedingly irritating and painful swellings. They are 

 closely allied species called the gold tail and brown tail 

 moths {I'ort/iesiii aurijliia and {■In-i/sDrrluFn). The moths 

 may be very easily recognized, as they are like no other 

 British insects ; they are of a satiny or creamy white 

 colour, the former having the hinder parts of its body 

 clothed with bright golden silky hairs, and the latter having 

 the same parts covered with soft down of a deep brown 

 colour. They are often very abundant, and then the cater- 

 pillars do a gi'eat deal of damage to hawthorn hedges, 

 sometimes absolutely stripping them of their bright spring 

 foliage. 



The caterpillar of the gold tail is the handsomer of the 

 two, as well as the more virulent. Its black body is 

 adorned with vermilion stripes and little warts, from which 

 spring clusters of white (Fig. 12) and 

 black hairs in pretty contrast. It has \ .i' , 



also on its back two orange, cup-shaped, 

 wax-like bodies, which are glands for 

 the secretion of an odoriferous and 

 easily vaporizable liquid. These cater- 

 pillars are common in the early summer, 

 and may easily be reared, but they 

 should on no account be touched. If 

 they are handled, and the hands are 

 then brought into contact with the 

 face or neck, large oval wales are pro- 

 duced on these parts in a few minutes, and these (juickly 

 become highly inflamed and itch intolerably ; rubbing, of 

 course, only aggravates the discomfort. After a while the 

 sweUings subside and the irritation is allayed, so that the 

 inconvenience is merely temporary ; still it is an extremely 

 undesirable experience while it lasts. 8ometimes merely 

 holding the head over the cage while the food is being 



FiG.12.— Clust»rof 

 white liairs from 

 hir\*ti of Guii.1 Tail 

 Moth. 



changed is sufficient to cause the symptoms to appear. No 

 doubt small fragments of the hairs are wafted about in the 

 air, and any little disturbance like that caused by putting 

 fresh food in brings them into contact with the skin. The 

 hairs retain their disagreeable power for a long time. 

 Many of them are woven up with the silk of the slight 

 cocoon the caterpillar makes when it becomes a chrysalis, 

 and if such a cocoon be pulled to pieces even long after- 

 wards, the operator not unfrequently suffers in consequence. 

 This seems to throw doubt upon the suspicion that the 

 hairs are poisonous, since it might be expected that a 

 poisonous secretion would be operative only when freshly 

 formed and still moist. The fluid above mentioned as 

 secreted by the glands on the back does not appear to be 

 used to supply the hairs, and indeed it is itself not of an 

 acid character, and hence is less likely to be able to pro- 

 duce irritation. The brown tail caterpillar, which is rather 

 like the gold tail, but not so brilliant, produces similar 

 results, but not in so marked a degree, at least in the 

 experience of some people ; but it must be admitted that the 

 testimony of entomologists varies on this point, and some 

 denounce the brown tail as the greater delinquent of the 

 two. Possibly the difference may be a matter of individual 

 temperament. In any case, collectors of caterpillars should 

 beware of these two species, and on no account handle 

 them ; indeed, it is safe to lay down the rule that, for their 

 own sakes quite as much as for the collector's, caterpillars 

 of whatever kind should be handled as little as possible. 



Other species in tropical countries produce results which 

 are even more disagreeable. Mr. Poulton once exhibited 

 to the Entomological Society of London a large hairy 

 caterpillar from the island of Celebes. It was described 

 by the natives as causing a complaint something like 

 erysipelas in those who touched it. The bristle-like hairs, 

 which were hollow and barbed, easily penetrated the skin 

 and then broke off. Of course, as the hairs were hollow, it 

 is probable that they contained a poison during the lifetime 

 of the insect, but as the specimen had been preserved in 

 spirit, that pomt could not be determined. The cater- 

 pillars of the processionary moths of the Continent, so 

 called from the wedge-shaped phalanx they form when 

 they go out to feed, produce great irritation, accompanied 

 by inflammation and eruptions of the skin, and their hairs 

 are not only barbed, but have been found to contain formic 

 acid, facts quite sufficient to account for the eft'ects produced. 



Glands for the secretion of protective liquids arc fre- 

 quently found on caterpillars, and are probably of much 

 commoner occurrence than has hitherto been suspected. 

 Almost all the members of the family Liparidce, to which 

 the gold tail and brown tail, as well as the " tussocks" 

 and " vapourers " belong, have been found by Mr. Poulton 

 to possess them. The caterpillar of the puss moth, again 

 (Fig. 13), has a large 

 gland just beneath its 

 mouth, from which 

 it can shoot forth 

 strong formic acid 

 with considerable 

 force, the expulsion 

 being caused in this 

 case as in others by 

 the partial eversion 

 of the gland, which 

 consists of a sort of 

 pocket in the skin. 

 The caterpillars of 

 certain saw - flies, 

 which are much like 

 those of moths, also have the power of squirting fluids with 



b-— 



Fia. 13. — Caterpillar of Puss Moth, in 

 terrifying attitude (after Poulton). a, 

 head ; A, position of formic acid gland. 



