BEET-LEAF MINERS: THEIR EGGS AND MINES. 205 



The Eggs. 

 The eggs are white, delicately reticulated, elongate-elliptical in form, 

 0.03 of an inch in length, and about one-third as broad (.075 mm. by 

 .024 mm). Their general appearance is shown in JFig. 

 60.* They are placed by the fly on the under sur- 

 face of the leaf, with few exceptions, — sometimes 

 singly, most frequently in twos attached by their sides, 

 often in threes, occasionally in fours, and in a very few 

 Fio. CO. — Eggs instances, five were seen together. Upon one leaf, du- 



of an Anthomvian, .,,■,,, ,i.ti ^ i ^ 



greatly enlarged, ring the latter part 01 July, when the eggs seemed 

 most abundant, thirty-seven were counted, of which about one-third 

 had given out their larva? or had been killed. They were distributed 

 over the entire surface of the leaf, but rather more numerously toward 

 the margin. A leaf free from eggs could rarely be found. 



The Mines, 



When the egg hatches, the young larva enters at once into the leaf. 

 Its burrow is at first quite narrow, scarcely exceeding the diameter of 

 the egg-shell, but it soon enlarges, and after proceeding a short dis- 

 tance, expands into an irregular blotch. When two or more eggs are 

 placed side by side, the larvae occupy the same burrow and the same 

 mined cavity. Their channels usually lead toward the outer edge of 

 the leaf and extend to the margin, where the mined portions, after 

 their abandonment by the mature larva, become dried and present the 

 appearance before described. Occasionally, the larvas find themselves 

 so crowded in one^portion of a leaf as to interfere with their food-sup- 

 ply, when some of the number emerge from their circumscribed quar- 

 ters and travel to other parts of the leaf, or to another leaf, where 

 they quickly gnaw through the epidermis and burrow beneath it. In 

 one instance in which the operation was watched by me, the larva (a 

 large one) had entirely hidden itself in fifteen minutes. 



The Flies from Pupse. 

 On August 7th, four of the flies emerged from pup^e, which had been 

 obtained from the larvte about two weeks before. On the 8th, several 

 of the infested leaves were gathered, and portions cut from them con- 

 taining about twenty-five of the larvse nearly full-grown. These were 

 placed in a glass jar of loose earth, and as the material was eaten, or 

 became unfit for food, as it speedily did, fresh pieces were supplied. As 



*The eggs of these species are longer than those shown in the figure ; the reticulations 

 also are longer and less regular, so that while their general shape is hexagonal, others are 

 but four-sided and of the form of a parallelogram, and others still of irregular form with 

 four, tivc or six unequal sides. 



