194 



Forty-first Report on the State Museum. 



sive, and had caused the leaves to wilt and shrivel to such a degree 

 that it was only by careful unfolding-, spreading and pressing that the 

 character of the mines could be made out. 



The Larval Mines Described. 

 The mines observed in the daisy were run with remarkable uni- 

 formity, commencing at a point 

 where there was indication of 

 egg-deposit, at the margin of the 

 foot-stalk of the leaf or at one of 

 the lower lobes, following closely 

 the margin up the lobe, excavat^ 

 ing it somewhat broadly at the 

 apex, then descending on the 

 opposite side, to turn and mine 

 the next higher lobe and follow- 

 ing ones in the same manner. A 

 characteristic feature of the mine 

 is its punctulation along its entire 

 length by small black grains of 

 larval excrement, deposited at 

 rather regular intervals, and 

 almost invariably on the marginal 

 side. An exception to this was 

 an instance where a wavy broad 

 channel had been run toward the 

 center of the leaf, in which the 

 excremental matter was not gran- 

 ular nor deposited marginally, 



but was diffused throughout the 

 Fig. 31. A daisy leaf showing the mines . . ,. . i • i 



and pupee of the Marguerite fly, Phytomyza mine — indicating plainly some 

 LATEEALis. abuormal condition of the larva. 



The mines do not always originate in the lobes. One was observed 

 to commence half-way down the stem of a leaf, and in another instance 

 almost at the base of the stem. They are run upon the upper side 

 of the leaves, just beneath the upper cuticle. 



Pupation within the Mines. 

 When the larva has attained its growth, it excavates a blotch-like 

 space on the lower side of the leaf, where it transforms to a pupa, • 

 which, covered only by the thin and transparent cuticle that in drying- 

 contracts over and closely about it, seems as if it were lying exposed 

 upon the outer surface. Its deeply incised segments show distinctly, 

 and its two subcylindrical contiguous anal spiracles — projected 



