Caterpillars---OG 12

[prachich1987]

Caterpillars of all species produce an identical hormone called "juvenile hormone" that maintains feeding behavior. Only when a caterpillar has grown to the right size for pupation to take place does a special enzyme halt the production of juvenile hormone. This enzyme can be synthesized and will, on being ingested by immature caterpillars, kill them by stopping them from feeding.

Which of the following, if true, most strongly supports the view that it would not be advisable to try to eradicate agricultural pests that go through a caterpillar stage by spraying croplands with the enzyme mentioned above?

(A) Most species of caterpillar are subject to some natural predation.
(B) Many agricultural pests do not go through a caterpillar stage.
(C) Many agriculturally beneficial insects go through a caterpillar stage.
(D) Since caterpillars of different species emerge at different times, several sprayings would be necessary.
(E) Although the enzyme has been synthesized in the laboratory, no large-scale production facilities exist as yet.

Source : OG 12
OA : C
Can someone explain why B is wrong?

[Geva@EconomistGMAT]

It's important to focus on what the question is asking,e specially when the question stem itself is such a long sentence. Paraphrase the question in your own words: the question is presenting a course of action (eradicate agricultural pests that go through a caterpillar stage by spraying croplands with the enzyme), and asks why it would not be advisable.
what you're looking for is some harmful side effect of the course of action - something that says "don't do it!".

B simply says that the course of action may not be enough, as it won't kill other pests. But it still does not say why it would be wrong to use the enzyme t kill those pests that do go through caterpillar stage - for these pests, the enzyme will get the job done.

C gives you the "don't do it" reason: you're also killing off the good insects as well.