OF WASHINGTON. 159 



while others have very long ones, is of interest. I have reared 

 and taken these short-winged forms under the most favorable 

 conditions for the full development of the wings, yet we often 

 find all of them with short wings. I also find the long-winged 

 forms developing under unfavorable conditions. What seems 

 most remarkable, however, is that in a large number of specimens 

 reared from eggs taken from a jar, in which all of the males 

 apparently had short wings, all of the males hatching from the 

 eggs had long wings. 



Three species of Sciara have been bred from potato tubers 

 during the investigation referred to. One of them was deter 

 mined by Dr. Williston as Sciara aliata. Another he deter 

 mined as probably a new species, which I will refer to, in this 

 connection, as Sciara species No. i. I have recently reared the 

 other species, which I will mention as Sciara species No. 2. The 

 larvae of species" No. i were found to have similar habits to 

 those of Epidapus scabiei, and can scarcely be distinguished 

 from them, except that the Sciara larvae are larger. The 

 abundance of this species in flower-pots in the greenhouse and in 

 windows and flying in the open air indicates that it must be quite 

 common. 



Sciara species No. 2 was reared from tubers showing the 

 characteristic injuries caused by Epidapus and Sciara species No. 

 I . The larvae and pupae were found in the dead tissue, but the 

 larvae were not observed, like the others, to feed on the living 

 tissue. 



"With the mass of evidence resulting from the extensive modern 

 investigation of the so-called potato-scab and the potato-rot, 

 which goes to prove that all forms of both these troubles are due 

 to parasitic fungi and bacteria, together with the fact that the 

 insect theory, with reference to their cause, has, it would appear, 

 been universally discarded by European and American investi 

 gators, it would seem the height of presumption upon my part 

 to claim that these insects are the cause of certain forms of both 

 scab and rot, or at least what are recognized as such. 



While I admit that one or more forms of the so-called potato- 

 scab may be due to the action of fungi, and that the true potato- 

 rot is a fungous disease, I am confident that there are forms 

 heretofore recognized as scab and rot which are not due to 

 fungous disease, but are the direct result of the attack of insects 

 belonging to the family Mycetophilidas and to the genera Sciara 

 and Epidapus. 



MORGAN-TOWN, WEST VA , May i, 



