LACHNEIDES. 441 



{Clisiocampa) or Tolype, which have ii and iii greatly reduced (two 

 hairs on ii and one or two only on iii in Malacosoma) in the first instar, 

 although, as Dyar says, the arrangement or position is the same. In 

 fact, there appears to be but little difference in the position of the 

 Lachneid larval tubercles, i and ii being trapezoidal, iii supraspiracular, 

 iv and v subspiracular, with a tendency to coalescence, and iv to be 

 pushed back posteriorly. 



Bacot says that the larval head forms a fairly good rough guide as 

 to a generalised or specialised first stage — the former being shiny and 

 the latter dull in appearance. Almost all the larvae examined, except 

 those of Eutricha quercifolia and Dendrolimus pint, have it shiny in the 

 first instar, whilst nearly all have it dull and often brightly-coloured 

 in the later stages. 



The larvae of the British Lachneids, according to Bacot, divide 

 broadly into two groups (with a possible third group for Poecilocampa 

 pojndi) : (1) The Lachneid group — neustria, castrensis, crataeiji, lanes- 

 tris,rubi,trifolii, querciis. (2) The Eutrichid group — potatoria, ilicifolia, 

 quercifolia. In the latter group E. quercifolia is much more specialised 

 than C. potatoria, and appears to be quite as highly developed among 

 the Eutrichids as does L. querciis among the Lachneids. The 

 larvae of the first group show a great deal of individual specialisation, 

 but the Malacosoma larvae are considered as perhaps nearest the 

 primitive form. The larvae of P. trifolii, L. querciis, and M. rubi have 

 the short secondary hairs developed into a loose fur, which easily rubs 

 off, and which, by the mechanical properties due to their small size, 

 delicacy, fineness, and sharpness, produce urtication if they enter the 

 skin. The startling coloration of some of these larvae — L. querciis, M. 

 rubi, &c. — which suddenly display their dark rings when disturbed, 

 probably has a warning significance, and this possibly has also been 

 the case at a previous time with the coloration still exhibited in the early 

 stages of P. populi, 21. rubi, &c, in which the rings or spots of colourexhi- 

 bited by the young larvae suggest strongly that this was at one time the 

 adult coloration and had a warning significance, but has now been 

 forced back to the early stages in favour of later and more success- 

 ful developments. There can be no doubt that the coloration of L. 

 querciis, E. quercifolia, &c, are marvellously protective when at rest. 

 Bacot considers that the oblique stripes are the most generalised larval 

 markings, but they are much modified in some species. The subdorsal 

 spots, dorsal coloured patches on the meso- and metathorax, as well as 

 the blue stripes and patches on the subdorsal and lateral areas are also 

 considered generalised characters, because remnants of them can be 

 traced in so many species. 



There is a tendency in some of the genera for the larvae to be 

 gregarious, and the habit is more particularly strong in the early stages 

 and rarely (if ever) maintained in the full-grown larvae. It is of course 

 less marked in those species which scatter their eggs. The larvae of 

 Malacosoma generally spin large silken webs which are common to a 

 whole brood, and this habit has obtained for them, in America, the 

 popular name of " tent " caterpillars. Still more conspicuous is the large 

 web, formed by Lachneis lanestris, which covers a considerable area, and 

 into which the larvae retire when not feeding or sunning themselves. 

 Others show no tendency to be gregarious, and rest, stretched out at 

 length on the twigs of their respective food-plants, their long sub- 



