345 



b.ased upon the experiiueats (incomplete though thej' were) of a French chemist who 

 passed here about a >^ ear ago and who died since in South America. — [John A. Spring, 

 Tucson, Arizona, August 21, 1887. 



Reply. — The portion of your letter of August 21, referring to the exudation of the 

 Creosote Bush {Larrea mexicana) has been referred to the Entomologist, who reports 

 that the specimens were received in good condition and that they form welcome ad- 

 ditions to the collections of the Entomological Division. Strange as it may seem, it 

 has been abundantly proven that this exudation is that of an insect and not directly 

 of the plant. The insect in question is the Carteria larreoe of Comstock, described 

 in the Annual Report of this Department for 1881-82, page 211. This insect belongs to 

 the Bark-lice or Coccidse, and to a peculiar group of these insects which secrete wax 

 and lac in different forms. It is closely related to the insect which produces the 

 stick lac of commerce and which is known as Carteria lacca Kerr. Another species 

 has been described by Professor Comstock, which appears upon Mimosa, in Mexico. 

 This he calls Carteria mexicana. You will find a good discussion of the characters of 

 these insects in the Annual Report of this Department just mentioned, and of the 

 insect theory as opposed t^. the plant theory, including also some remarks upon the 

 chemical properties of lac in the American Naturalist, Vol. XIV, p. 782 (November, 

 1880). You will also find the chemical properties of the stick lac of commerce treated 

 in most of the chemical dictionaries or encyclopaedias. — [August 31, 1387.] 



A Rhizococcus on Grass in Dakota. 



Inclosed please find two spears of grass with some eggs of something that I wish 

 .you to determine for me if you can, as the grass is infested with it all over this coun- 

 try. If you don't experiment with such things please hand it to some one who does. 

 If they do not hatch until spring, a warm place and a little sprinkling would bring 

 them to life. If they are injurious to stock let me know, as there are lots of horses 

 and cattle running out here. — [A. E. Hall, Buffalo Gap, Custer County, Dak., Feb- 

 ruary, 1888. 



Reply. — Your letter of recent date inclosing spears of grass with eggs laid in white 

 sacs has been received and referred to the Entomologist, who reports that the white 

 waxy sac is excreted by a bark-louse which seems to be a new species of the genus 

 Rhizococcus. Up to the tinje of depositing the eggs the wingless degraded females 

 of this insect are naked, but as the time for oviposition approaches they begin to 

 secrete this smooth white sac all over the surface of the body, and as the secretion 

 becomes thick they begin depositing their eggs, moving forward in the sac thus 

 formed and after death shriveling up and remaining in the anterior portion. It 

 will probably not have the slightest deleterious effect upon the stock. — [February 18, 

 1888. ] 



Wash for Apple-tree Bark-lice and Borers. 



I find the most effectual wash for bark-lice on apple and pear trees and borers in 

 apple and peach trees to be the following recipe: 5 pounds of potash (Babbitts's the 

 best) and 5 pounds of lard dissolved in 5 gallons of boiling water; 1 peck good stone 



I lime slacked in 5 gallons boiling water, while hot mixed with potash and lard. The 

 above mixture can be kept in an old tub or barrel for any length of time. To use add to 



i each gallon 2 gallons of boiling water, and while hot apply to trunk and large limbs 

 with an old broom. If this mixture is applied to treos while young and used year 

 after year, the bark of the trees will be kept as smooth as glass and all bark-lice and 

 borers destroyed. — [J. Luther Bowers, Herndon, Va., February 24, 1888. 



Saw-fly on Polygonum dunietoruni. 



To-day I mail a box containing same larvic that may interest you. This is the 

 first colony I have seen of them. They were found on wild grape vine, also on another 

 climber, Polygonum danielornni, which I enclose, and have the peculiarity of curling 



