300 THE ENTOMOLOGIST. 



DESCRIPTION OF THE EGG OF POLYOMMATUS CORYDON. 

 By F. W. Frohawk, M.B.O.U., F.E.S. 



As I believe there is no published description of the egg of 

 this common butterfly, the following is a description taken down 

 in my note-book on Aug. 16th last, after figuring the specimen. 

 I should state that I examined several ova to check the one 

 described. 



On Aug. 13th, 1900, I watched several females in the act of 

 depositing, on various stems of the usual stunted herbage to be 

 found growing on chalk downs. They frequently crawled among 

 the plants for a distance of about a couple of feet, occasionally 

 curving the abdomen downwards among the small plant-sterna 

 and grasses, and here and there deposited an egg. I therefore 

 dug up portions of the turf, potted it, and placed a couple of 

 females on each lot; they deposited ova on the 14th and 15th, 

 on the stems of the various plants ; a few were laid upon the 

 brown dead trefoil leaves, as well as on the living leaves ; but the 

 site generally chosen is the intermingled stems of both plants 

 and grasses. Another female, placed upon a similar pot of plants, 

 deposited about fifty ova on Sept. 10th, nearly all being placed 

 upon the stems, and a few upon the under side of the leaves of 

 rock-rose ; in all cases the eggs are deposited singly. 



" The egg is ^ in. in diameter and ^ in. high ; it differs in 

 shape from all the other eggs of the ' blues ' which I have 

 examined ; instead of having a concaved surface above, it is flat, 

 with merely the micropyle sunken ; it is also higher in pro- 

 portion, and the sides are almost perpendicular ; the base is 

 flattened, the micropyle is very finely punctured, an irregular 

 network pattern covers the upper surface and gradually increases 

 in size to the outer rim, where it develops into a beautiful lace- 

 like pattern, which is considerably bolder than that of the other 

 * blues' ' eggs with which I am acquainted. The reticulations 

 are united by very large prominent projecting knobs, and vary 

 in number from five to seven. The sunken spaces between are 

 very finely granulated. The colour when first laid is almost 

 white, mainly caused by the whiteness of the glass-like reticula- 

 tions and knobs, the colouring gradually changing to a slightly 

 greenish grey hue." 



As the egg does not hatch until the following spring, the 

 reason for no particular plant being selected as a site for the 

 egg is at once apparent, as necessarily all the plants die off in 

 the winter and become an entangled mass of withered stems. 

 The young larva, upon emerging in the spring, must then search 

 for the fresh growth of its proper food-plant. 



September, 1900, 



