147 



"curly" or "birds-eye" poplar, was the resiil^ of tlie injury in the bark 

 by woodpeckers. 



The imtatoHcab gnat. — During November I obtained a fresh supply of 

 material for the continuation of an investigation, commenced in Septem- 

 ber, 1891, to determine the relation of certain dipterous larv.e to the 

 so-called potato scab and to certain other injuries to the i)otato tuber. 

 This investigation has resulted in the determination of some interest 

 ing facts, among which I may mention in this connection the following : 



First. That two species of so-called fuugous gnats MycetopIiylid;e, one a Sciara, 

 the other an Epidapus, will attack and feed npon healthy vegetable tissue; a fact 

 regarding the habits of the Mycetophilid which, I believe, has never before been 

 demonstrated. It was also determined that the latter species, w^hich I have 

 described under the name of Epidapus scabies, will develop from eggs to imago in the 

 healthy or sound substance of potato tubers. 



Second. That the larva of Epidapus scabies will cause injuries in the outer portion 

 of potato tubers which would be recognized as so-called potato scab, and that under 

 favorable conditions they will feed upon the tubers until all but the epidermis is con- 

 sumed. 



Third. That the presence of stable manure and decomposing vegetable matter in 

 the soil, together with moisture, are the most favorable conditions for the presence 

 of these insects, and that under such conditions serious loss is caiised by them to 

 potato growers. 



It may be of interest to note that the male of Ejrida^jus scabies is 

 the first male of the genus ever recorded, although the genus has been: 

 known in Europe for over fifty years. Some of the results of the 

 investigation were presented to the uewlj^-formed State Horticultural 

 Society on April 6, and in a j)aper read before the Washington Ento- 

 mological Society on May 3, 1894. In the latter a full description, 

 with illustrations of all stages of the species, was presented, and will 

 be publi.shed in the Proceedings. The former will be published in the 

 Proceedings of the State Horticultural Society. 



The following observations not noted in the above papers may be 

 mentioned here: On February 3, a Proctotrypid, determined by Mr. 

 Ashmead as Ceraphron hasaiis Ashm., was observed to be quite com- 

 mon in company with the Epidapus in the mushroom beds and on the 

 floor in the greenhouse. It was also reared from manure infested by 

 the scab gnat. It is, therefore, probably a parasite of this sj)ecies. 



Several species of Staphyliuidte were also common in the beds 

 infested by the Epidapus, and as they increased in numbers the gnats 

 decreased, and finally became so rare that it was scarcely possible to 

 find an example. Philonthus longieornis Steph., P. nigritulus Grav., 

 Xantholinus cephalns Say., and Homalota Uvidipennis Mann., all deter- 

 mined for me by Mr. Schwarz, were among the species met with in the 

 manure, A', cephalns and H. lividipennis being especially common. 



A Ccramhycid in walnut wood. — January 18, an undetermined Cer- 

 ambycid larva was found inhabiting the sound heart wood of living 

 black walnut. This, together with large species of black ants which 

 enlarged the mines of the wood-boring larva, cause serious damage in 

 this valuable wood. 



5210— No. 2 7 



