LASIOCAMPA. 37 



i. L. quercus (English) : Dorsal (urticating) fur dull white to pale dusky- 

 brown. Head dull indigo. 



2. L. var. callunae (Scotland) : Dorsal fur dull brown. Head dull indigo. 



3. L. var. meridionalis (Cannes) : Dorsal fur pure white. Head, orange-red. 



4. L. var. viburni (Cannes) : Dorsal fur red-brown. Head orange-red. 



5. L. var. sicula (Sicily) : Dorsal fur red-brown. Head orange-red. 



Bacot further notes : " In the English races, the head of the adult 

 larva is of a deep indigo-blue, occasionally tinged with orange on the 

 cheeks ; in the continental forms the head is normally orange-red, the 

 clypeal marks being whitish ; the latter are usually faint or absent in 

 larvae of the English races. Adult continental larvae appear to be more 

 densely haired than English. In the early stadia the difference is much 

 greater, the south of France larvae assuming the adult plumage in the 2nd 

 or 3rd stadium, while those of English parentage do not attain the full 

 development of hairs, until at least one if not two moults later. Larvae 

 of Z. var. meridionalis and Z. var. viburni axe indistinguishable before 

 the growth of the urticating fur; the divergence of the coloration then 

 becomes more marked at each successive ecdysis. The larvae of the 

 English races are more variable than those of the French, the 

 variable points being the greater or less development of the oblique 

 stripes and the development of the blue shading laterally ; the blue 

 is generally stronger in English larvae, and the dorsal fur of the latter 

 varies from dull white to pale brown, &c. Other interesting points 

 mentioned by Bacot (Ent. Record, xiii., pp. 114 — 116 et seq.) are 

 the rapidity with which larvae of Z. hybr. meridionalis X callunae 

 fed up — three to four months from hatching to spinning (August to 

 November, 1897) — followed by a pupal stage of from 20 — 30 months, 

 all but one or two finally dying. He also notes that when the 

 English race is crossed with a foreign race, the former stamps its 

 peculiarities most markedly on the progeny. When Z. var. meridionalis 

 and Z. var. viburni are crossed, the resulting larvae, as we have 

 already noted, divided into two distinct groups following the parents 

 — one with white urticating fur, the other with golden-brown — there 

 were no intermediates. When Z. hybr. bacoti (meridionalis X viburni) 

 is crossed with either of the parent races, the larvae tend some- 

 times to revert wholly to the form characteristic of the race with 

 which the cross is paired, at others to split into two moieties — one 

 white-haired, the other golden-haired. The most remarkable general 

 result is that by crossing two forms (meridionalis and viburni) 

 occupying the same geographical area, we get a separation of the 

 larvae into two groups following the parental types, whilst in crossing 

 two forms (meridionalis and callunae) occupying far distant geographical 

 areas, we get a blending of the parental larval peculiarities, and 

 what may be termed intermediates between the two forms. Full 

 details of the modifications obtained in the various broods have 

 been published Ent. Record, xiii., pp. 143 — 144. 



The following is a summary of the results obtained by the 

 crossing of the two south of France forms, me7'idionalis and viburni, 

 and their progeny. There appears to have been some little doubt* 

 whether the first, 1896, cross should be called viburni X meridionalis or 



* Bacot's original notes {Ent. Rec., xiii., pp 1 14 et seq.) are written viburni x 

 meridionalis, leaving one to assume that the parentage was <? viburni x ? merid- 

 ionalis ; as a matter of fact the parentage was <? meridionalis x ¥ viburni, and this 

 is used in Warburg's notes (loc. cit., pp. 237 et seq.). 



