In the next chapter, the image of the wasp occurs again. The two English Christian missionaries, Mr. Graysford and Mr. Sorley, are in the habit of discussing the extent to which the animal kingdom might share in divine bliss (presumably after death). They discuss this question with their Hindu friends. Mr. Sorley believes that monkeys might be so blessed, but he is less sure about jackals, even though he thinks the mercy of God might well extend to all mammals. But he is uneasy, as a Christian, about extending this to wasps.
The third occurrence of the wasp image occurs in Part 3, when Professor Godbole is performing the religious ceremony. Into his mind at almost the same time drift the images of Mrs. Moore and of a wasp, two images that "melt into the universal warmth." Since there is no sign that one is worth more than the other to him, this suggests the difference between the Indian and the Christian view of things.
A Passage to India: Metaphor Analysis