BUREAU OF ENTOMOLOGY AXD PLANT QUARANTINE 49 
should not be applied commercially to any vegetable crop to be used 
as food until more information is available as to the possible health 
hazard incurred. 
Red Spiders Succumb to Systemic Insecticide 
Aerosols, sprays, or drenches containing the systemic insecticide 
octamethyl pyrophosphoramide (OMPA) have proved very effective 
against red spider mites on greenhouse-grown roses, ageratum. carna- 
tion, dahlia, and chrysanthemum. This was true even with the strains 
of mites that are resistant to other insecticides. Preparations con- 
taining OMPA were effective also against aphids infesting these crops, 
but, in the same dosages, they were not toxic to such other common 
greenhouse pests as thrips. whiteflies. mealybugs, or several species of 
chewing insects. These results are of immediate importance to green- 
house operators, who are currently faced with the problem of com- 
bating resistant red spider mites on ornamental plants. Certain 
strains of the mites have developed a resistance to aerosols contain- 
ing parathion. hexaethyl tetraphosphate, tetraethyl pyrophosphate, 
tetraethyl dithiopyrophosphate, and some other insecticides that for- 
merly gave effective control. 
Research, in cooperation with the Bureau of Plant Industry, Soils, 
and Agricultural Engineering, showed that octamethyl pyrophos- 
phoramide is absorbed through the leaves, stems, or roots of treated 
plants, depending on the method of application. The absorbed mate- 
rial enters the sap stream of the plant and moves up the stem from 
the roots or lower leaves to the upper leaves and buds. Here it 
becomes sufficiently concentrated in a few days after application to 
be toxic to red spider mites and aphids feeding on the sap in those 
parts. It does not move down the stem from upper leaves to lower 
ones or from the leaves to the roots. 
In experiments in the Bureau's greenhouses at Beltsville. Md., and 
in commercial greenhouses, aerosols containing either 5 percent or 
10 percent of octamethyl pyrophosphoramide. with methyl chloride 
as the propellent gas. gave excellent results against mites and aphids 
on roses. The dosage was at the rate of 1 pound to 50,000 cubic feet 
of either the 5-percent or the 10-percent formulation or at the rate of 
1 pound to 100,000 cubic feet of the 10-percent formulation. Xo 
serious injur}- resulted to five commonly grown varieties of roses. 
Best results were obtained, however, when the insecticide was applied 
to young and vigorously growing plants, because octamethyl pyro- 
phosphoramide is more readily absorbed by the younger foliage/ 
Octamethyl pyrophosphoramide was also effective against spider 
mites and aphids on ageratum, carnation, rose, dahlia, and chrysan- 
themum when applied lightly as a mist spray to the tops of the plants 
in greenhouses. The spray consisted of a 1 to 1,000 water dilution of 
the technical material containing 60 to 70 percent of the active in- 
gredient, with a small quantity of wetting agent. Eight weekly appli- 
cations were tolerated without injury by Better Times and Briarcliffe 
roses, but they caused slight to moderate yellowing () f the older leaves 
on Starlight. Golden Rapture, and Cavalier roses. 
A single drench of octamethyl pyrophosphoramide applied to the 
soil in flowerpots containing roses or lilies was taken up by the roots 
