500 Journal of Agricultural Research voi. x, no. ic 



Picraena excelsa. He studied various methods of extracting quassiin and 

 "picrasmin," as he called the bitter constituent of P. excelsa. In 1891 

 Shimoyama and Hirano (40) described Picrasma ailantoides Planch. 

 They found a crystalline principle in the bark which corresponded to 

 quassiin. Four years later Merck (24) separated a substance which he 

 called "quassol" from impure quassiin by solution in ether. Its melt- 

 ing point was found to be 149° to 150° C, while that of pure quassiin is 

 210° to 211°. It is further distinguished from quassiin by its tasteless- 

 ness. In the same year Hooper (16) obtained from Ailanthus excelsa an 

 extremely bitter substance resembling quassiin. According to Dragen- 

 dorff (5), Simaruba excelsa, a Brazilian species, is used as a remedy for 

 intestinal worms and for skin parasites. 



According to the preceding review the principal constituents of quassia 

 are quassiin, picrasmin, quassol, an alkaloid (?), a volatile oil (?), resin, 

 mucilage, and pectin. The constitutions of the first three are not defi- 

 nitely known, and the actual presence of the volatile oil and alkaloid has 

 not been definitely established. 



2. — LITERATURE DEALING WITH QUASSIA EXTRACT AS AN INSECTICIDE 



It is reported that quassia extract has been used as an insecticide in 

 Europe for many years, but the earliest authentic record found by the 

 writers occurs in 1885. On this date Ormerod (30) reports that the hop 

 growers in England found quassia extract efficient upon the hop aphis. 

 The proportion of ingredients used was generally 6 pounds of quassia 

 chips and 3 pounds of soft soap to 100 gallons of water. 



Alwood (i) prepared a decoction of quassia by using i pound of chips 

 to 2 gallons of water. He says : 



Applied pure, it killed the lice (hop aphid) effectually where they were reached, 

 but it will not spread. Only those under drops were killed. Diluted once it was 

 still quite effective, but could not be used with any thoroughness. I do not consider 

 this a practical remedy when used alone. 



Smith (41, 42, 43) prepared a strong decoction of quassia and applied it 

 externally and internally to rose chafers (Macrodactylus suhspinosus Fab.). 

 He claims that it was ineffective, regardless of how it was applied. 



Riley and Howard (36, 37), basing their deduction upon the results of 

 Alwood's experiments (i), report that quassia extract when used alone 

 is greatly inferior to well-prepared kerosene emulsion for hop aphids. 



Koebele (20) sprayed hop aphids on prune trees in the States of Oregon 

 and Washington with a solution prepared in the proportion of 6 pounds 

 of quassia chips and 3 pounds of soap to 100 gallons of water. He says: 



The numerous ants attending the Aphidids were not destroyed by this wash, and 

 they carried off the lice not destroyed by the application the following day, leaving 

 the immature lice dead upon the leaves. The action of the quassia is very slow and 

 considerable time elapses before the lice are all destroyed. 



