230 REPORT OF TITE COMMISSIONER OF AGRICULTURE. 



there had been bo signs of silk in their mines. Tlie spinning of the 

 cocoona in every instance studied occupied about two days, and the 

 larvae transformed in a very few hours thereafter to i)upae, in which 

 stage they presumably, under ordinary conditions, remained until the 

 putting f< rth of green leaves. In the breeding room, hov.ever, kept at 

 an average temperature of 68° F., the moths began to issue on March 

 20, 15 days after the transformation, nearly double the time in which 

 the raidsummer brood remained in this state. 



EEIVIEDY. 



From a brief review of the natural history of tlie inr.ect under con- 

 sideration, it would seem that an efiicient remedy would be readily found 

 in raking ux) and burning the fallen leaves during winter, when they 

 contain the hibernating round-form larvae. This would, indeed, in the 

 majority of cases, prove all-suf&cient. But, unfortunately, there are 

 oaks the dead leaves of which cling persistently to the twigs through, 

 out the whole winter ; so that upon the department grounds, for example, 

 although all leaves are carefully collected late every fall, there still re- 

 main enough on the trees to start a bounteous crop of leaf-miners the 

 next season. The saving of leaves for manure is a doubtful economy 

 when infested with leaf-miners like L. hamadryadella. If the collecting 

 of the leaves be posti^oned untd spring, the startjjig buds wiU have 

 forced them oSi without exception, and the miners can be completely 

 destroyed. 



FITCH'S OAK-LEAF MINEE. 



{LitJiocoUetis Fitcliella Clem.) 



Order Lepidoptera ; family Tineidae. 



Forming a tentiform mine on tlie tmder surfaces of the leaves of different oakS; a 

 minute, nearly cylindrical, wLite larva. 



TJlion the under sides of the oak leaves during the past summer were 

 found many niines of this insect, described years ago by Dr. Fitch.* 

 Although belonging to the same genus as the insect which we have just 

 described, and although resembling it considerably in the adult form, in 

 its early stages and in the character of its mine L. Fitcliella presents 

 maiked differences. 



From the empty shells which we find abundantly upon the underside 

 of the leaf the egg seems to be very similar to that of L. hamadryadella. 

 Its greatest diameter is .116"'", and in shape it is lentiform. From two 

 to a dozen of these egg-shells will often be found on the under surface 

 of a leaf upon which there is but a single mine, and when we take this 

 fact in connection with the number of larvae that are parasitized we 

 can see the small proportion which the insects arridng at maturity bear 

 to the number of eggs origin all j' laid by the female moth. 



The newly hatched larvae do not vary sufficiently from those full 

 grown to merit special remark. The mine, unlike tbat of L. hamadry- 

 adella, is i)}ainly evident fi'om both sides of the leaf. It belongs to that 

 group of mines called tentiform, from the fact that the under cuticle 



•Fifth N. Y. Eept., sec. 327, nnder the unme of Argyromige^ qtun-cifoliella. After- 

 wards redescribed l;)y Clemens (Proc-. Aca-d. Nat. Sci. Phiia., 1S60, *207), Fitch's name 

 being preoccupied. See Chambers's Index to N. A. Tiuein?, Ball. U, S. Geol. (Survey, 

 vol. iv, No. 5, p. 154. 



