1S47.] Insects Injurious to Vegetation. 3 



in number, size, and position; and sometimes nearly all disap- 

 pear. A little while before hatching, two lateral rows of opaque 

 white spots, about ten in number, can be seen in each egg. In 

 four days, more or less, according to the weather, the egg is 

 hatched." 



The Larva. Growth of the worm, or active larva. — Mr. Her- 

 rick's excellent description is continued as follows, " The little 

 winged maggot, or larva, creeps out of the delicate membranous 

 egg skin, crawls down the leaf, enters the sheath, and proceeds 

 along the stalk, (see fig. m,) usually as far as the next joint be- 

 low," (fig. B. §§,) or, in other words, to the base of the sheath, 

 which in the young autumnal wheat, is at the crown of the root 

 (fig. A. §). " Here it fastens, lengthwise, (fig. n and o,) and 

 head downwards, to the tender stalk, and lives upon the sap. It 

 does not gnaw the stalk, nor does it enter the central cavity there- 

 of; but, as the larva increases in size, it gradually becomes em- 

 bedded in the substance of the stalk. After taking its station, 

 the larva moves no more, gradually loses its reddish color, and 

 w^rinkled appearance, becomes plump and torpid, is at first semi- 

 translucent, and then more and more clouded wnth internal white 

 spots; and when near maturity, the middle of the intestinal parts 

 is of a greenish color. In five or six weeks (varying with the 

 season,) the larva begins to turn brown, and soon becomes of a 

 britrht chestnut color, bearing some resemblance to a flax-seed," 



&C. 



Its characters. — When freshly taken from the root of the wheat 

 the mature worm (fig. g) measures about fifteen hundredths of an 

 inch (0.15) in length, by about 0.06 in breadth. It shows no 

 signs of life when placed upon paper and turned over wuth a nee- 

 dle-point. It is soft, glabrous, shining, white, oval and appa- 

 rently composed of but nine segments, although twelve can often 

 be distinctly perceived before its growth is completed. These are 

 quite slightly marked by faint transverse lines of a greenish-brown 

 hue. Its under side is flattened, and has an ablong grass-green 

 cloud or spot in the middle, placed longitudinally. No regular 

 contractions or crenatures occur along the margin to mark the 

 segments, though after the worm has laid exposed to the air an 

 hour, the color of the transverse lines above spoken of becomes 

 bleached out as it were, and then, perhaps from the worm's hav- 

 ing become somewhat dried, faintly impressed transverse lines are 

 perceptible at the junction of each of the nine segments: faint 

 longitudinal striae are also discernable, as though produced by the 

 pressure of the parallel veins or ribs of the sheath and culm, be-, 

 tween which the worm had laid. 



Its mode of feeding. We have hitherto sought in vain to., as- 

 certain, by ocular and microscopic examinations, how it is that 



