457 



Hexacladia smithii sp. no v. 



Male : Length 1.8 millimeters ; wing expanse 4 millimeters. Head brownish- yellow, 

 smooth, polished, the vertex fuscous; face very convex, with a few scattered, shallow 

 punctures. Eyes broadly oval, brown. Antennte black, the scape pale rufous, with 

 a dusky streak above, the six fnuiclar joints each furnished with a long hairy branch. 

 Thorax black, impunctured, highly polished; collar brownish-yellow; scutellum 

 shiuing, but microscopically shagreened. Anterior legs, including coxte, brownish- 

 yellow ; middle and posterior legs black: in the middle pair the knees, tips of tibiae, 

 tibial spur, and tarsi are brownish-yellow. Abdomen black, the dorsum concave, 

 probably unnaturally so in the dry specimen. Wings hyaline, with two transverse 

 brown bands that do not extend entirely across the wing, terminating at about its 

 center; the first and narrower is situated at about two-thirds the length of the sub- 

 costal vein, the second and broader one just beneath the marginal. 



Female: Length 2 millimeters. Head much wider than in the male, and except a 

 streak on the face below the base of the antennae, entirely black. Antennae sub- 

 clavate, brown, the scape and pedicel rufous. Thorax above black, highly polished : 

 the basal half of the scutellum is bright red; collar, mesopleurae, anterior legs, mid- 

 dle coxae, tips of middle and posterior tibiae, and their tarsi, rufous ; the rest of the 

 legs dark fuscous. Abdomen short, rather strongly compressed, black, shining. The 

 apical half of the anterior wings, except the margins, is wholly brown, the basal 

 half hyaline, with the narrow subcostal band as in the male. 



Described from ooe 9 and two '^ specimeus, taken by Mr. Herbert 

 H Smith, at Cbapada, South America, during the mouth of April, and 

 in honor of whom this beautiful chalcid is named. 



HISTORY OF THE HYDROCYANIC ACID GAS TREATMENT FOR 



SCALE INSECTS. 



By D. W. CoQUiLLETT, Special Agent. 



So far as I am aware no persou ever used hydrocyanic acid gas for 

 the purpose of destroying insects on trees or plants prior to the time 

 that the writer was employed by Professor Eiley, Chief of the Division 

 of Entomology, United States Department of Agriculture, in the sum- 

 mer of 1886, to carry on a series of experiments for the destruction of 

 the Fluted or Cottony-cushion scale {Icerya purcliasi Maskell). 



In the month of September of the above-mentioned year I first began 

 experimenting with this gas by confining the trees in an air-tight ves- 

 sel, and then filling the latter with the gas generated from potassium 

 cyanide and sulphuric acid i^laced within the vessel. At first I oper- 

 ated on small orange trees, using a common 5-gallon kerosene can, 

 the entire upper end of which had been i:>reviously removed. After 

 placing the generator upon the ground at the base of the tree to be 

 operated upon I next placed the necessary chemicals in the generator 

 and immediately covered both the tree and the generator with the tin 

 can inverted over them, the lower edge of the can having been firmly 

 pressed into the earth to prevent the escape of the gas. 



