THE BUTTERFLIES OF THE 

 BRITISH ISLES. 



PART I. 



THE LIFE CYCLE OF A BUTTERFLY. 



As is the case with all other Lepidoptera, butterflies pass 

 through three very distinct stages before they attain the perfect 

 form. These stages are : — i. The egg (ovum, plural ova), 

 2. The caterpillar {larva, iarvoz). 3. The chrysalis {pupa, 

 pupce). The perfect insect is called the imago (plural imagines). 



The Egg. 



Butterfly eggs are of various forms, and whilst in some kinds 

 the egg-shell (chorion) is elaborately ribbed or fluted, others 

 are simply pitted or covered with a kind of network or reticula- 

 tion ; others, again, are almost or quite smooth. If the top of an 

 egg, such as that of the Purple Emperor (Plate 28), is examined 

 under a good lens a depression will be noted, and in this will 

 be seen a neat and starlike kind of ornamentation. In the 

 middle of this " rosette " are, present in all eggs, minute aper- 

 tures known as micropyles (little doors), and it is through these 

 that the spermatozoa of the male finds entry to the interior of 

 the egg and fertilization is effected. The changes that occur in 

 the egg after it is laid are of a very complex nature, and readers 



