THE YOUNG NATURALIST. 



181 



I am free to admit that the seasonal influences do not seem to me suffi- 

 cient to account for all the phenomena. How, for instance, does the mild 

 winter and cold spring affect adversely those Pieridce that pass the winter 

 as pupse, of which several are in the list to follow ? 



Mr. Decie objects, however, not only to the assigned cause for the dis- 

 appearance of our butterflies, but also to the assumption " that the time is 

 not very far distant when a large proportion will have ceased to exist as 

 natives." Yet he only appears able to put off the evil day, and to persuade him- 

 self that " though there is certainly a process of extinction going on, — yet 

 the time is exceedingly far distant," &c. The more li exceedingly far distant" 

 the better, say I, and I had no idea of limiting the period so narrowly as 

 Mr. Decie appears to have understood me. A thousand years is but a swing 

 of the pendulum in the great timepiece of nature. 



I will now run over the various species already named in my paper, or by 

 others, and see what has been advanced that can lead us to satisfactory con- 

 clusions. Mr. Decie must forgive me if I am brief, but the paper must not 

 be inordinately long. 



1. Papilio Machaon. — Is admittedly restricted to a very narrow area 

 now. It bred at Beverly in Yorkshire, in 1 803 (see Porritt's " Yorkshire 

 Lepidoptera," page 7.) It disappeared from Dorset in 1816. It was once 

 a common garden insect in the suburbs of London, and is yet to be found in 

 lanes and gardens over the greater part of the Continent. It passes the 

 winter as a pupa. Why it is becoming so restricted does not appear to be 

 satisfactorily determined. 



2. Leucophasia Sinapis. — Not named by me, but Mr. Clifford calls 

 attention to it as a species now scarcer than formerly, which he attributes to 

 the ungenial springs killing the female ere oviposition. 



3. Pieris CraTtEGI. — Mr. Dale tells that it disappeared from Dorset in 

 1815, Hybernates as a small larva. It has long been known to have 

 become much scarcer than formerly. 



4. Pieris Daplidic^;.— Mr. Jobson (p. 96) has taken this on three 

 separate occasions between Cambridge and Newmarket, and is confident it 

 breeds there, in the proper sense of the term, one of the specimens being 

 hardly dry when found. If it bred there it could be taken regularly, not three 

 times only in the course of an Entomologist's career. There is no doubt it was 

 once of regular occurrence, but it is rarely taken now, except at that part of the 

 coast nearest Prance. Like Machaon it passes the winter as a pupa, and I 

 know no reason why it should not be as abundant as the three Common 

 Whites. 



