U)4 

 The Corn T>kaf-mtnku. 



nidstdlil sp. 



Not inrivqiuMilly corn U^;i\i's ;in> in;u'k(>(l liy siM-ptMit ii\o liu'hl-colorod 

 tracks, oausocl l\v iniinito l;u"v:v hurrowiiii;' within tlu> leaf, (h^vtnirinii; 

 the inner tissues, aiul leaving the senntrans[)arent rpiilorniis intact. 

 Iiarva> from burrows of this kind t)bserved by us in Illinois liave usually 

 been those of leaf-niining moths. 



The present species, however, is a Hy belonginj:; to the Crom!/::id(V, a 

 family cU)sely related to the frit-tlics (O.'^rinidd). The other larva^ of 

 the family live, so far as known, in the sIcmus of plants. Thos(> of this 

 species were found by Comstot'k* in corn leaves in the south i)art of 

 Washington, 1). C. The mines were abtnit a tiMith of an inch wide and 

 five or six inches long. Thc>y wcmv (piite abundant, \\\rcc or fom- to a 

 leaf, and situated ncvir the tnlge. Th(> lar\;e wer(> about a tifth of an 

 inch U>ng, greenish white, with arclunl back and a pig-like anterior enil. 



These mities were noticinl lati> in ,Inn(\ About July 12 the larva^ 

 began to matun^ and break through tlu^ upper epidei-mis, drojiping to 

 the ground. .Inst beneath the sm-face they transfornuHl to oval brown 

 pu[)aria, and three weeks later a shining black adult tly about an eighth 

 of an inch long emerged, apparently an undescribed species of Diastata. 



Tlu> same species was reported by .\shmead as quite frequently met 

 with in corn leaves in Florida. 



The STALK-AiAocior. 

 Chcrtopsis a-nca Wied. 



The yellowish maggots of this very common and widely distributed 

 fly are frequently fountl in the stalks and under the leaf-sheaths of a 

 number of crop and other plants, usually in tlu^ midst of more or less 

 ilecaying tissue. In many cases, possibly in all, tlu\\ are acting as 

 scavengers in a previous injury, but they undoubtcnlly greatly aggravate 

 the original wound, and there is reason to b(>li(>v(> that healthy plants 

 are also attacked by them. 



These larva^ (l^'ig- 153, a) :uv about a (piarter o\' an inch long and a 

 twenty-fifth of an inch thick, footless, yellowish, the head end tapering 

 and slender, the posterim- end suddenly and bluntly rounded off, with 

 two short, brown, cylindrical projections. They are found in tluM'orn- 

 stalk, usually not far abo\(> or below the sm-face of the grouml, or 

 behind a leaf-sheath. Young larva^ apjiarently of this species have been 

 found by us in broom-corn roots, and once in a buri-ow in a corn root. 



TluMr injury is often conunon and consjiicuous in wheat and oats, the 

 upper part of the atTected plants withering and whitening. In 1S94 it 



♦Rep. U. S. Ent., 18S0. p. 245. 



