1S47.] Insects Injurious to Vegetation. 6 



^ye very much doubt. The worm is nouiished and reared upon 

 those very fluids that are absorbed by the plant and elaborated for 

 its own sustenance and growth. Every particle of this nutricious 

 juice, therefore, that is consumed by the worm, is a direct loss of 

 just so much material that would otherwise become straw and 

 grain. At all events, we think our farmers generally will prefer 

 that nature should be left to her own undisturbed course in rear- 

 ing their wheat plants, and will be by no means solicitous to have 

 this renowned guest take any part in the operation. 



Its change to a '■'Jlax-seed^' or dormant larva. When the worm, 

 or active larva, has fully completed its growth, a slight diminu- 

 tion in the dimensions of the inner soft parts of its body com- 

 mences, in which the outer and harder skin does not participate, 

 this latter retaining its original full size. The result of this con- 

 traction is, that the worm gradually cleaves from its outer skin. 

 If examined with a microscope when this change has recently 

 commenced, a slight translucent space is observable at the head 

 end, and a larger and more obvious one at the pointed or tail end, 

 plainly indicating that the enclosed worm does not entirely fill its 

 outer skin. This contraction continues, until the worm becomes 

 entirely separated from its outer skin, and lies within.it like the 

 finger within a glove. The outer skin at the same time changes 

 in color. From its original whiteness and transparency, it gi-ad- 

 ually becomes opake, brown, and finally of a dark bay or chestnut 

 color. Though much less flat than a flax seed, its resemblance 

 in color, size and form to that familiar object, is so striking as at 

 once to be remarked by every one. 



Characters of the flax seed, or larva case. Different specimens 

 of these flax seed like larva cases (fig. h. i. j.) vary in length from 

 0.13 to 0.19 and in breadth from 0.05 to 0.08. They are shining, 

 cylindrical-oval, more obtusely rounded at the lower or head end 

 than at the other, which is generally attenuated into an acuminat- 

 ed point or small projecting papilla. They are commonly com- 

 posed of but nine obvious segments, and these are but slightly 

 indicated by very faint acutely impressed transverse striae — a sim- 

 ilar transverse stria, but still more faint, being sometimes percep- 

 tible (fig. h.) across the middle of some of the segments. Longi- 

 tudinal impressed striffi are sometimes present, (fig- J.) more con- 

 spicuous than the transverse, and reaching a part or the whole 

 length of the worm; and between these the surface is minutely 

 acuducted (i. e. appearing as if lightly scratched by the fine point 

 of a needle) longitudinally — all these longitudinal impressions 

 being perhaps caused by the pressure of the veins and fibres of 

 the plant, against which the worm has been imbedded. On the 

 under side, (fig. i.) towards the head end, the case is flattened, as 

 if pinched together, so much so that the anterior seg^ment seems a 



