LEPIDOPTERA. 267 



(Colias Edusa), which, as Mr. Newman notes, is usually 

 visible, sometimes exceedingly plentiful, every four 

 years. The Camherwell Beauty, generally exceedingly 

 rare, has been seen to come afield in a " flock," as have 

 others of its more brilliant comrades, the Peacock, &c. 

 The Leopard Moth, an insect so rare as to be formerly 

 sold at a guinea a specimen, abounded about ten years 

 ago to such a degree, that nearly all the young trees 

 in Euston Square, and the copse plantations of ash in 

 many parts of the country were destroyed by its pith- 

 eating Iarva3. 



This may be partly accounted for by the power pos- 

 sessed by some Lepidoptera, of remaining long in the 

 pupa state. Sphinx Ligustri has been known to remain 

 in the Chrysalis for three years, while Mr. John Sircow 

 records the coming out of a Moth after six years of 

 incarceration. It may be supposed that a particularly 

 favourable season brings to perfection the insects of many 

 preceding years. 



Mr. Douglas notes that weather has an effect upon 

 the hatching of Lepidoptera, a warm rain after drought 

 being favourable to this process. In some cases a great 

 abundance of particular Butterflies has been accounted 

 for by their having lived through the winter, thus adding 

 the numbers of one year to those of another. 



