'THi; LlFE-UiSTOilY OF A LEl'IDOl'tEllOtJS iNSECf. l^f 



1893, pp. 451-6, but the conclusion at which Professor Poulton arrived 

 did away with the notion that there Avas any regularity in the pro- 

 duction of the sexes from successively-laid eggs. On the contrary, " it 

 was found that the relative proportion of the sexes was subject to 

 immense fluctuation on the separate dates on which eggs were laid. As 

 regards eggs laid on any one day, the sexes generally succeeded each 

 other in little groups of irregular size. No law of succession of the 

 sexes could be established." 



Bearing on this, is another observation recorded in the Trans. Linn. 

 Soc. of London, vol. v., 1890, p. 156, in which Messrs. Jackson and 

 Salter found that the pupaj obtained from different batches of Vanessa io, 

 had a large proportion of a certain sex, some batches producing almost 

 entirely males, others consisting almost entirely of females. Such 

 batches, of course, would greatly aid the inter-crossing of the species, 

 and tliis state of things is much more probable than that the sexes 

 alternate in successively-laid eggs with anything like regularity. 



10. — On the duration of tue egg stage. — This varies very greatly 

 but depends to a considerable extent upon whether the eggs hatch the 

 same year they are laid, or whether hybernation takes place in the egg- 

 state, and in the latter case upon the time of year at which the eggs 

 are laid. Mr. Fenn (Eat. Rec, vol. iii., pp. 175-76), Dr. Buckell (I.e., 

 p. 255) and Mr. Prout (I.e., vol. iv., p. 292) have recorded some obser- 

 vations bearing upon the question as regards the Gteojietr.e. Of those 

 species whose eggs hatched the same year in which they were laid, the 

 gi'eater number remained in the egg stage from a week to a fortnight. 

 The shortest period recorded by JMr. Fenn is two days in the case of 

 Acidalia vm/nlaria ; by Dr. Buckell, four days in the case of Timandra 

 amataria, and many species have a period of only five days. On the 

 other hand, some species have a much longer period, as will be seen by 

 the following instances from the above-mentioned articles : Selenm 

 telralanaria, 23 days ; Biston hirtaria, 17 to 37 days ; Ampliidasys 

 strataria, 30 days ; Hemerophila abruptaria, 14 to 26 days ; Boarmia 

 ahietaria, 19 days; B. geminaria, 20 days; Hyhernia leucophearm, 38 

 days ; Larentia caesiata, 24 days, &c. The period varies for the same 

 species in different years, possibly depending on meterological con- 

 ditions. Selenia hilunaria has the following record : — 1860, 1st brood, 

 16 days ; 1883, 1st brood, 28 days, 2nd brood, 16 days ; 1890 and 1891, 

 2nd brood, 15 days. Selenia limaria took 7 days in 1865, 12 in 1861, 

 and 15 in 1886 — all 1st brood. Of Carnptogramnia Jinviata in 1865, 

 one batch took 5 days, another 10 days and a third 21 days. 



11. — On hybernation in the egg stage. — As indicated in the 

 preceding paragraph, some sj^ecies are known to hybernate in the egg- 

 stage. To what extent this obtains among insects is, perhaps, hardly 

 as yet ascertained with any degree of certainty, but among Lepidoptera 

 there would appear to be scarcely any large group in which some of 

 the species do not pass the winter in this state. Of our British butter- 

 flies Lycaena aegon and Pamphila coiiDiia arc reported to ^J'lss the winter 

 as ova, whilst several of the Thcclidi certainly do so — among our species, 

 ThecJa, quercns, T. betulae, T. w.-alhum and T. prnni — whilst allied species 

 do so in America. Scudder says that some of tlie Clirysojilninidi winter 

 in this state ; tlie Paruassidi also do so, at least Fariiassias apoUo does. 

 Among the Bujibyces a large number of s})ecies, as Orgyia antiqna, 

 liybernatt,' in this stage, so also do a large number of Geojietu.i}, 



