affecting the Com- Crops. 
153 
To plough in March, or the beginning of April, would destroy 
the larvcB and prevent the escape of the flies ; but burning the 
stubble is strongly recommended. 
An Ichneumon, named Pachymerus calcitrator, punctures the 
larvse which become the prey of the young parasitic maggots. 
This Jiy is abundant, in June and July, in various parts of 
England. 
It is doubtful if the Hessian jly has ever been detected in Europe. 
In North America it has occasioned famine by its ravages 
amongst the wheat. 
This fly, or an allied species, attacked the wheat-crops in Hun- 
gary in 1833. 
Two-thirds of the straw was laid, and produced only abortive 
ears. 
These larval lived in families between the sheath-leaf and the 
straw, near to the crown of the root. 
The larvce of ihe Hessian Jly also live between the sheath and 
the stem, close to the base. 
A parasitic fly, called Ceraphron destructor, keeps the Hessian 
fly in check. 
Larvce of the British wheat-midge detected in July, 1795, 
attacking from one to several grains in an ear. 
The infested grains appeared yellow, or prematurely ripe. 
They contained an orange-coloured powder and minute yel- 
lowish-white or deep yellow larvce. 
The same larvce, Mr. Markwick says, inhabit the husks of the 
" wild bearded oat," Avena fatua. 
Some agriculturists in Sussex formed an idea at first that the 
larvce did no mischief to the corn. 
The Wheat-midge was very abundant the middle of July, 1797. 
These Jlies had spotted or rather obscurely clouded wings. 
The larvcB were exceedingly abundant later in the season, but 
very few pupce were found. 
One of the Jlies was bred in September, but they probably do 
not generally hatch till the spring. 
As many as seven or eight ^florets in an ear inhabited by the 
larvce, and as many as thirty in a single floret. 
The pupce never found within the Jlorets where the larvce re- 
sided. 
Parasitic Ichneumons destroy the greater part of the larvze. 
The larvce feed upon the pollen, and the geriuen never swells. 
In June, 1798, there were innumerable hosts of the female 
Wheat-midge, but not any males : twelve at one time were laying 
eggs in a single ear. 
They begin to Jly about seven in the evening and disappear 
about Jii7ie o'clock. 
