BEET AND SPINACH INSECTS 



. 91 



Fig. G1. — The spinach leaf-miner, adult 

 (X4). 



nettle-leaved goosefoot, common chickweed and lady's thumb 

 (Polygon u m persicaria) . 



The flies appear in the fields in April or May. They are 

 about J inch in length, grayish in color and clothed with numer- 

 ous black seise ; the legs 

 are yellowish with the 

 tarsi blackish (Fig. 61). 

 The female deposits her 

 eggs singly or in rows of 

 two to five placed side 

 by side on the underside 

 of the leaves (Fig. G2). 

 The egg is about 2V ii^<^'h 

 in length, white, cylin- 

 drical, and the surface 

 is distinctly reticulated. 

 The eggs are attached 

 to the leaf by one side; they hatch in four to six days and 

 the young maggot works its way into the tissue of the leaf 

 where it eats out a mine between the upper and lower epi- 

 dermis. The mine is at first thread-like but is soon enlarged 

 to form a blotch. Several maggots usually 

 occupy the same leaf and their mines usually 

 coalesce. In the course of its growth the 

 maggot molts twice, thus passing through 

 three stages. If the food material in a single 

 leaf becomes exhausted, the maggots may 

 I'iG. 62. — Eggs migrate to another leaf in order to complete 

 of the spinach their growth. In case the leaf dies, the masr- 



leaf-miner (X ^ . . . i • i i 



31). gots are able to complete then- development 



on manure or humus, according to observations 



made in Hungary. The larva becomes full-grown in a week 



to sixteen days. It is then ^ inch in length, white or 



yellowish with the hook-like mouth-parts black. The body 



