516 BBITISH LEPIDOPTEKA. 



years on March 4th- 5th. Hervey records that two specimens that 

 pupated on July 8th, 1869, did not emerge until March 18th, 1874. 

 Bladen observes that larva? taken at Burghclere on June 23rd, 1879, 

 produced imagines on March 6th, 1881, January 1st, 1882, March 3rd, 

 1883, and April 2nd, 1884. Slade reports that 100 pupas were obtained 

 from a nest of larvae taken in 1869 at Buckingham, of these 15 emerged 

 in February, 1870, 12 in February, 1871, a few in February, 1872, and 

 a few in 1873. Larva? obtained by Todd in 1866, produced about 100 

 pupae ; of these the first moth emerged February 2nd, 1867, others 

 following, in 1868, the next emergence was on February 20th, 1869, then 

 on April 6th, 1869, whilst others remained in thg pupal stage after this 

 date. Adkin records that he fed up a brood of larvae in 1891, there were 

 no emergences in 1892, but about a half of the pupae disclosed imagines 

 in the early spring of 1893. Larvae obtained August, 1896, at Poulton, 

 several imagines emerged March 21st-April 25th, 1897, some lying 

 over (Clutten); an imago emerged February, 1897, from an 1894 larva 

 (Moss). Gribble notes that from a larva taken at Stokesley in 1895, 

 a female emerged February 18th, 1898. Atmore observes that he has 

 reared moths from four-year-old cocoons. Bobson also notes that his 

 brother at Stockton-on-Tees, reared a number, some of which emerged 

 on almost the same day in February, over six or seven years. Baker 

 says that he found the larvae common at Chagford in 1887, these 

 pupated in due course, and the imagines emerged over a period of four 

 years. Speyer observes that from Waldeck larvae which pupated in 1855, 

 part of the imagines emerged March, 1856, two in 1857, and the last 

 female in February, 1859. He further notes (Stett. Ent. Zeit., xlix., 

 p. 205) that to pass a second year in the pupal stage is quite an 

 ordinary thing, also a third, once he knew of a fourth, but in June, 

 1882, two larvae of this species pupated, tbe pupa from one of these 

 larvae, kept in an unheated room, produced an imago April 4th, 1887, 

 whilst the other was still a pupa on July 16th, 1888, and then showed 

 no sign of wing-development although living and quite healthy. It 

 finally emerged on April 9th, 1889. The emergence of an imago 

 after a pupal stage lasting five years is mentioned by Treitscbke. 

 Zeller, of Balgrist, records examples of L. var. arbusculae going over 

 in the pupal stage for eight winters, and then emerging ; Standfuss 

 also obtained several imagines of this form after a pupal stage 

 extending over four and six winters. The cause of this delay in 

 emergence is not known. It certainly is not lack of temperature at 

 the right time, for of many pupae subjected to identical conditions, 

 some emerge, others go over. Edmunds records that in 1860, many 

 pupae kept in a warm room went over until another season, yet two 

 kept in a cold cellar emerged on April 5th and 7th. Pierret con- 

 sidered that the delay was caused by the hardness of the cocoon of this 

 species, which rendered it impenetrable to the vivifying action of the 

 air, and asserted that those species which had exceptionally hard 

 cocoons were those which remained longest in the pupal state (Ann. 

 Soc. Ent. France, 1846, p. xl). The most remarkable factor in the 

 case is that living organisms, whose tissues must perform at least 

 some vital functions, can live such a long period of time without 

 food and without apparently drawing on their own reserve material (if 

 any) and ultimately produce a perfect insect of full size and colour, 

 and differing in no way apparently from that which would have been 



