- 504 - 
Nicotine sulphate (40 percent) sprays were tested against 
aphids ( kacrosiphu m liriodendri Mon. , k. rosae L. , Chaitophoru s po pu l i- 
cola Thos. , Myzus persicae , and Aphi s sp,). The results show that 
nicotine sulphate acts very quickly, while quassia extract o,cts 
very slowly. The results also indicate that a shower 2 hours after 
the application of these insecticides does not affect the efficiency 
of the nicotine sulphate, while it greatly reduces the efficiency of 
quassia extract (pp. 515-518). Nicotine a,cts quickly, causes pro- 
nounced symptoms, and kills by paralysis (p. 528). 
SAPRO, V. I. (2141) 
1917. HOW TO Tx,ST POR THE PRESENCE OP NICOTINE ON SPRaYED PLANTS. 
Jour. Econ. Ent. 10: 459-451. [Abstract in Rev, Appl. Ent. (A) 
6; 18-19. 1918.] 
Tests confirmed the belief that nicotine may be present 
and continue to have some action for a considerable time after the 
spray had dried. On the sprayed foliage a film of nicotine re- 
mains which may still act as an insecticide. 
TROOP, J., and MASON, P. to". (2142) 
1917. SOiJB COMMON GARDEN INSECTS. Ind. ^gr. Expt. Sta. Circ. 64, 
pp. 1-15, illus. 
Under contact insecticides, nicotine sulphate and tobacco dust 
are briefly described (p. 14). The latter acts in two ways; it kills 
through the breathing pores, and it also acts as a repellent. 
MOORE, torn. (2143) 
1918. OBSERVATIONS ON THE LODE OP ACTION OP CONTACT INSECTICIDES. 
Jour. Econ. Ent. 11 (6): 443-445. [Abstract in Rev. Appl. 
Ent. (A) 7: 115-116. 1919.] 
Insecticides containing oil or soap may penetrate the tracheae 
of the insect thus preventing normal oxidation from taking plc-ce in 
the insect's body, with the result that the insect dies from their 
mechanical action alone. Nicotine may produce death by chemical 
action without materially influencing the intake of oxygen. The 
efficacy of free nicotine sprays is found to be increased sometimes 
by 50 percent ^oy the addition of soap. 
mOORE, w'm. and GRAHAM, S. A. (2144) 
1916. PHYSICAL PROPERTIES GOVERNING THE EPPICACY OP CONTACT INSECTICIDES. 
Jour. Agr. Res. 13: 523-536. [Abstract in Rev. Appl. Ent. (.a) 
5; 397-398. 1916.] 
Contact insecticides may be divided into two groups (l) those 
that wet but which do not spread, owing to their adhesion being less 
than their cohesion and (2) those that wet and spread over the surface 
and are able to gain entrance to the tracheae by capillarity since 
