are employed concurrently or successively. For example, various cultural 
and mechanical measures can be used to get adequate control with limited 
chemical treatments; or various measures, including chemical treatment, 
can be used together with parasites and predators ina single control 
pattern. This approach is called integrated control. 
Some entomologists believe that the integrated-control approach isa 
necessity in modern agriculture. 
The integrated control concept has been put into practice in a number 
of instances, especially in California for the control of the alfalfa cater- 
pillar and the spotted alfalfa aphid attacking alfalfa, and the cyclamen mite 
on strawberries. 
Beneficial insects can sometimes survive treatments with aninsecticide 
of short residual action if it is properly chosen and used. For example, it 
may be applied when the beneficial insects are ina resistant stage. Or it 
may be used so the beneficialinsectis not readily exposed to the insecticide. 
Or areas can be left untreated so a reservoir of beneficial insects will be 
spared. 
In one California experiment involving the rotational treatment ofa 
citrus grove with chemicals to control the purple scale, only one-third of 
the trees were treated each year. The remaining two-thirds sustained a 
reservoir of beneficial insects. In 5 yearsthis practice achieved exceptional 
control of the scale at a reduced spray cost. 
California entomologists also applied the principles of integrated control 
against the spotted alfalfa aphid. They applied a systemic insecticide, which 
is absorbed into the plants. The chemicalinthe plant juices killed the plant- 
sucking aphid, butits parasites and predators, not plant feeders, were spared. 
ARS entomologists found that when the tobacco budworm and tobacco 
hornworm were both infesting tobacco at the same time, top treatment of 
the plants with an insecticide gave good control of these pests in the upper 
leaves where they were most abundant. This restricted treatment spared 
the lower leaves from heavy insecticidal residues and gave Polistes wasps 
an opportunity to prey on the lighter hornworm populations on those parts 
of the plant. 
In some cases the environment of a parasite or predator may be modi- 
fied in such a way that the beneficial insect can operate to better advantage 
and thus reduce the amount of chemical controlneeded. The parasites might 
be provided with better food--certain nectar-bearing plants, for example-- 
and they might be protected from secondary parasites or predators. Some 
parasites cannot tolerate the presence of ants that gather to feed on the 
honeydew of scale insects on citrus; control of the ants in such instances 
enhances the value of the parasites. 
California workers showed that airborne dust oncitrus foliage adversely 
affected the activity of parasites of the California red scale. Reduced soil 
tillage, growing of permanent cover crops in the groves, and irrigation by 
overhead sprinklers are being tried to reduce the amount of dust in the 
grove, and at the same time improve temperature, humidity, and light 
conditions for the parasites. 
Proper timing of treatments has been used repeatedly to gain a degree 
of selective action with insecticides. Obviously, unnecessary treatments 
should be avoided and minimum dosages of insecticides used to gain the 
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