96 
plants, associated with the appearance of swarms of small, black- 
ish, gnat-like flies. An assistant of the ofiice, Mr. E, C. Green, was 
sent to the scene of the injnry to investigate and experiment, and 
this acconnt is mainly a summary of the results secured by him 
then. 
The flies belong to the family Myccfophilidcr, or fungus flies, 
and to the genus Sciara. The larvae of this large family seem to feed 
primarily on decaying vegetable matter, and records of their directly 
attacking healthy living plant tissues are rare. However, as is 
often the case with insects of this habit, their presence in decayed 
parts of plants, or even in close association with plants, seems in 
some way to promote decay. The larvcC of this genus are small, 
slender, glassy white, footless maggots, a third of an inch long or 
less, and usually with black heads. A species common in wet corn 
fields following sod, which sometimes eats the softened seed corn, 
especially in cold, wet springs, is treated in the eighteenth report 
of this office, where it is called the black-headed grass-maggot. The 
frequent occurrence of similar larvre in rich soil, especially in flower- 
pots and greenhouses, is also mentioned in that article. 
Mr. Green found numerous cases of the excessive abundance of 
such larv?e in the soil of forcing-house benches, and swarms of the 
flies, often in such numbers as to blacken the woodwork. The close 
association of these maggots with wilted and ruined beds of plants, 
and the invariable presence of numerous larvae about the bases and 
roots of wilting plants, strongly indicate that these larvje were the 
cause of the injury. 
When the cucumber plant wilts in the presence of these Sciara 
larvre, the lower leaves are affected first. These droop and finally 
hang down, gradually dying from the edges inward until the whole 
leaf is dried and shriveled. The rootlets and smaller roots of wilted 
plants are dark-colored and dead. The maggots are usually exces- 
sively numerous in the soil about such plants, often especially so 
about the main stalk. In no case were the maggots found attack- 
ing a firm, healthy stalk or root, but at the least appearance of decay 
they attacked it in great numbers, gnawing the surface and tunnel- 
ing thru it in all directions. If the larv?e are full-grown and 
rapidlv pupating at the time, and the flies are also beginning to ap- 
pear in large numbers, the plant usually survives the injury without 
assistance, showing signs of recovery in a day or two. An exami- 
nation of a plant at this stage shows numberless little, white, new 
rootlets starting from the main stalk and larger roots. If, how- 
ever, the maggots remain and continue their work several da}'S after 
the first wilting of the plants, these do not recover. 
In the fields these maggots have been noticed mostly in May 
and lune. but indoors and in hothouses they may occur at any time 
of the year, and the life cycle is probably rather short, so that there 
