Watt. — Ova of some of the Lepidoptera of TV ew Zealand. 65 



Art. XIII. — Descriptions of the Ova of some of the Lepidoptera of New 



Zealand. 



By Morris N. Watt. 



[Read before the Wanganui Philosophical Society, 11th August, 1913.] 



Plates I, II. 



I should first like to express my thanks to Mr. G. V. Hudson, of Wellington, 

 whose kindness and help in identifying many of the species the eggs of which 

 are described herein have been of no small assistance and encouragement 

 to me. I am also greatly indebted to Mr. R. Murdoch, who gave me most 

 valuable help in the preparation of the drawings and photographs. I shall 

 always recognize a heavy debt of gratitude to both Mr. Hudson and Mr. 

 Murdoch. 



This paper is practically opening up a new branch of entomology in New 

 Zealand. Hitherto the study of the eggs of our Lepidoptera has hardly 

 been touched upon, though a beginning was made by the late Mr. Ambrose 

 Quail, whose papers on the subject appear in the Transactions (vol. 33, 

 p. 159, pi. ix ; vol. 34, p. 226, pi. xiii). It has only been during the last 

 few years that the importance of the subject has been recognized in England 

 and on the Continent, and even in this short time an abundance of new 

 and important scientific data has been published. Formerly entomologists 

 confined themselves to elaborate and extensive descriptions of the adult 

 insects only, considering the study of the larvae and ova as of no im- 

 portance ; these were small and often microscopically minute, and were 

 therefore unworthy of notice. This idea is now exploded, and even more 

 importance is being attached to the accurate descriptions of the primary 

 forms of life and their development than to that of the adult forms. 



Turning now to the paper itself, there are one or two items and terms 

 that need some explanation. The eggs of all Lepidoptera are divisible 

 into two classes or groups, known technically as " upright " and " flat " 

 eggs. The shell is divisible into a base, walls, and apex. At the apex 

 there is, as a rule, a microscopic depression, from the base of which minute 

 canals lead into the egg, and carry the spermatozoa for the purpose of 

 fertilization. This is known as the micropyle. The external character- 

 istics of the micropyle generally take the form of a rosette of minute, 

 delicately sculptured, elongated cells. We are now in a position to define 

 the terms " upright " and " flat " : if the egg be so laid that the micropylar 

 axis is horizontal to the surface on which it is laid it is called a " flat " 

 egg, and if laid so that the micropylar axis is vertical to the surface on which 

 it is laid it is termed an "upright" one. Although the micropyle is actu- 

 ally at the apex in an " upright " egg, yet, on the other hand, it is at one 

 extremity of the long axis in " flat " eggs. The term " base," as hitherto 

 used by lepidopterists, is a doubtful quantity. It may be that side by 

 which the egg is usually attached to the surface of the food plant or other 

 object on which it may be deposited by the parent, or, on the other hand, 

 the side opposite the micropyle may be termed the " base." It follows, 

 therefore, that we speak of a Noctuid egg as being laid on its base, and, 

 to get rid of the anomaly, we speak of a Geometrid egg as being laid on its 

 long side. We use the term " base " as being the side opposite the micro- 



3— Traus. 



