38 



HARDWICKE'S SCIENCE-GOSSIP. 



creaff adds a fact worth remembering ; namely, that 

 of all the remedial applications he tried, a bruised 

 dock-leaf was the most effective. 



This gentleman's conclusion as to the cause is, 

 that it is produced by the hairs, which, when they 

 are separated, either through the moultings or by 

 the insect forming its cocoon, shortly become dry 

 and pulverulent, and when set in motion attach 

 themselves in minute particles to the face or hands. 

 But we are still in doubt as to " the reason why." 

 There must be some quality in this powdery sub- 

 stance which gives it this disagreeable activity. 

 And again, one asks : " As this influence produced 

 upon the human subject can hardly be the sole pur- 

 pose for which the caterpillar possesses it, in what 

 way does it operate otherwise for the defence of the 

 creature ; does it, for instance, prevent birds from 

 seizing gold-tail caterpillars ? " From the colours 

 of the caterpillar, it is certainly exposed to special 

 danger when near maturity. 



We find three hypotheses have been presented for 

 our consideration : that already noticed, which con- 

 nects the urticating effect with the hairs, and which 

 has this in its favour, that it is at those times when 

 the hairs are shed the caterpillar is most undesir- 

 able as an acquaintance. Others have, however, 

 ascribed its property to the separation or discharge 

 of some powdery substance, or scales, or flakes, 

 when it is irritated or alarmed. And yet again 

 others, turning from solids to fluids, imagine that 

 an acid secretion is the agent, which the caterpillar 

 fires off, in the manner of our well-known and 

 comical - looking caterpillar, commonly called the 

 Puss. It is rather against the latter supposition, 

 that so extensive an effect is produced on the skin 

 as often happens. Like the gentleman already 

 mentioned, I have attempted some dealings with 

 the species in its larval stage, in order to elucidate 

 this, and other puzzles in its history. But I must 

 own that the result of nurturing it in confinement 

 was sufiiciently painful to compel me to turn out 

 my captives ere the experiments were completed, 

 and I, for my part, now leave the practical part in 

 the hands of those who are almost callous to this 

 annoyance ; for there are some persons so far fortu- 

 nate — whether it is because they are thick-skinned, 

 I cannot detei-mine. 



Some particulars I was able to ascertain, though 

 it might be scarcely wise to generalize from these. 

 The young larva in the autumn seems to cause 

 little, if any annoyance, not even at the times of 

 moulting ; and the effect at a later period is more 

 marked upon a moist skin, with a high temperature, 

 than in cool weather, when the surface of the body 

 is drier. Examination of the skin of the face while 

 in a state of irritation failed to show any hairs or 

 particles discernible by the naked eye; but a 

 magnifier was not applied, which would have been 

 helpful. 



A correspondent of Science-Gossip has recently 

 remarked that the " Gold-tail " caterpillar ought 

 not to be placed among web- weaving caterpillars, 

 since all it spins is a slight cocoon for its protection 

 during the winter. This accords precisely with my 

 own observations, and yet in many authors we find 

 both this and the " Brown-tail " spoken of as gre- 

 garious, and therefore as architects of a common 

 abode for their accommodation and protection. 

 Bennie, indeed, figures the nests in his "Insect 

 Architecture," and states that the broods of the 

 " Gold-tail " and " Brown-tail " pass the winter in 

 closely-woven nests, and corroborates this by the 

 assertion that he observed at least twenty of these 

 in the winter of 1828. He could hardly have been 

 mistaken, nor is it credible that he would wilfully 

 falsify facts ; but it is possible that the species have 

 somewhat modified their habits since our winters 

 have been milder. Forty-four years have made some 

 difference in our climate, and I think it must be 

 admitted that we have less cold weather now than 

 formerly, and also tliat mostly our winter sets in 

 later. I should suppose, therefore, that from this 

 cause the caterpillars feed on farther into the 

 autumn, and, having scattered about, each one sub- 

 sequently spins up a small cocoon for itself, in 

 which it casts its skin, and then forms an inner 

 cocoon. The observations of other entomologists 

 may put the matter in a different light, but when- 

 ever I have found these, either in autumn ere 

 hybernation, or during the spring and summer, 

 they have been solitary. 



To distinguish these two nearly-allied species is a 

 difliculty to the beginner, especially in the cater- 

 pillar state. And even with the moths we are 

 liable to err, for the chief distinction is the colouring 

 of the tuft at the tail; and though between a golden 

 hue and a golden brown there is a marked dif- 

 ference, I have seen specimens in some series of 

 these insects seemingly intermediate in tint. The 

 black spot, however, always to be found at the anal 

 angle of the fore-wings in auriflua, is scarcely ever 

 present in chrysorrhoea. The latter I take to be on 

 an average the larger insect ; and thus I differ from 

 " Stainton's Manual," which gives us a statement 

 just the reverse. The caterpillars have a close re- 

 semblance, only in the "Brown-tail" tlie red stripe 

 on the back is less distinctly defined ; and, taken 

 altogether, it appears to a judge rather more gay in 

 its colouring, when placed beside its relative. As to 

 food, the "Brown-tail " shows a penchant for willow 

 and oak, also the blackthorn, being rarely seen on 

 the whitethorn, which is so generally favoured by 

 the " Gold-tail " caterpillar. J. B. S. C. 



"The most difficult thing a person experiences, 

 who comes into contact with geological teaching 

 for the first time, is the demand made on his im- 

 agination for the article of Time 1 "—Taylor's 

 Geological Stories. 



