1847.] Insects Injurious to Vegetatioii. 7 



niencing when the worm becomes a flax seed. Inaccuracies of 

 this kind, which to the general reader appear so trivial as scarcely 

 to require correcting, are liable to lead to important errors. Of 

 this, we have a striking illustration in this very instance. Mr. 

 Westwood, on opening the flax seeds contained in the wheat straw 

 from Germany, came upon " the larva," where, according to all 

 the accounts of the Hessian fly he ought to have found the pupa; 

 he therefore at once draws the important inference, that the Ger- 

 man insect cannot be the Hessian fly of America. Indeed it is 

 surprising, that so plain a fact as this, that it is a worm and not 

 a pupa which is enveloped in the flax seed case of our insect, has 

 been so wholly overlooked by every one who has hitherto written 

 upon this subject. 



The Pupa. When fanned. — On the access of the first warm 

 days of spring, as soon as the weather becomes suflSciently genial 

 for some of our earliest plants to put forth their blossoms, the 

 larva of the Hessian fly is rapidly stimulated to maturity. The 

 present year, so early as the 21st of April, most of the insects 

 were found to have taken on their pupa form. As this season 

 was more forward than usual, this may prove to be an earlier 

 date than is common for this occurrence; a more accurate criterion 

 by which to indicate it definitely, is no doubt by a reference to 

 the progress which vegetation has made at this time. We may 

 therefore state, that in all parts of our country, the Hessian fly 

 will probably be found in its fully formed pupa state, about a 

 w^eek after the liverwort, (Hepatica triloba,) the trailing arbutus 

 (Epigcea repens), and the red or swamp maple (^Jlcer rubrum,) 

 first appear in bloom, and simultaneously with the flowering of 

 the dry strawberry (Comaropsis fragarioides), the common five- 

 finger (^Potentilla canadensis), the hill-side violet (Viola ovata), 

 &c. It continues in this state about ten or twelve days, and then 

 sends out the winged fly. 



Its characters. — The flax seed shell has now become quite 

 brittle, breaking asunder transversely if rudely handled, and one 

 of its ends slipping oflT from the inclosed pupa like a thimble 

 from the end of the finger. On removing the pupa (fig. /) from 

 its case, it is found to be 0.13 long by 0.05 broad, of an oval 

 form, with rounded ends, and having its limbs and body enveloped 

 in separate membranes. The thoracic portion is slightly narrower 

 than the abdominal. The wings do not quite attain the middle 

 of the length of the body. The outer pair of feet come out from 

 under the tips of the wings, and reach to the anterior margin of 

 the penultimate abdominal segment, slightly curving inwards at 

 their tips. The next pair of feet are somewhat shorter, and the 

 inner pair are shorter still. They all lie in contact with each 

 other, and in a direction nearly parallel with the body. The ab- 



