432 
'Plie Progress of the Hessian Fly^ 
falling on the ground. Infested fields of wheat and barlej 
appeared to the casual observer as if cattle or sheep had been 
through them. Barley suffered more, perhaps, than wheat on 
the whole, and the attack was generally more severe on badly 
farmed land and upon poor, stony, or badly drained spots, and 
banks : or rather, the plants being weak were not able to bear 
up against the sap-draining effects of the larvae upon them. 
Wheat-plants of a stiff-strawed nature certainly showed the 
action of the insect upon them less than those of a less stout 
habit of growth. It follows, therefore, that upon well-farmed 
land with a strong, regular plant, the results would not be so 
serious as in the case of poor and indifferently cultivated soils. 
The drought also in these conditions tended to make the plants 
stunted, and more liable to receive injuries from insects. I\o 
special sorts of wheat were particularised as resisting the attack, 
but generally those of strong growth were noticed to have 
sustained the least damage. In experiments made in California 
it was proved that certain varieties of wheat were not affected 
by the Hessian Fly, while others growing in adjoining plots 
were extensively infested. A barley grower in Suffolk is of 
opinion that the finer sorts of barley, such as the Golden Melon 
and Peerless White, were more infested this season than more 
common kinds. But the question of the liability of certain 
sorts to the attack of the insect, and the comparative immunity 
of others, requires careful examination, and observations will be 
made in future seasons in order to determine this if possible, 
and to discover "fly-proof" varieties, as the Americans profess 
to have achieved. Packard says : " Of the different varieties of 
' fly-proof wheat, the Underbill variety has for a century been 
highly recommended. As Fitch remarks, its fly-proof qualities 
were supposed by many to be due to the hardness or solidity 
of its straw. The fl}' laid its eggs freely upon the leaves, but 
it was seldom if ever materially injured by it."* Further, 
Packard states that in Michigan the " Clawson " is app^irently 
the favourite wheat on account of its fly-proof qualities. 
The actual amount of loss sustained by this attack has varied 
much. In some cases not more than one stem in a square rood 
of ground could be found infested with pupa-cases. In others 
there were three or four per cent, of the stems having pupa-cases 
upon them. Upon a farm in Cambridgeshire it appeared as if 
there were at least ten per cent, of the stems attacked in certain 
fields ; while in other fields adjoining no traces of the insect 
could be found. There had been no difference in the methods 
• ' The Hessian Fly.' By A. S. Packard, M.D. Department of the Interior, 
United States Eutomological Commisjion, Bulletin No. 4. 
