There are many instances in the poem that the writer has used language to create impressions and contrasts.
In using the word "diabolic" (line 3) for instance, the scorpion is seen as being an evil or cruel creature. The poet also uses the metaphor of "the Evil One" (line 5) to describe the scorpion. This contrasts with the his overall portrayal of the scorpion as not being the villain as it was "driven" (line 2) from the constant rain to take shelter beneath a sack of rice and then having to "risk the rain again" (line 4) after the peasants came, presumably scared of them.
Another contrast is found when the neighbours have "peace of understanding" (line 14) while the poet's mother lay "twisted groaning on a mat" (line 16). It is incongruous that they are at peace because of her pain. They are not doing anything apparent to the woman while she is suffering.
The poet compares the peasants to "swarm of flies" (line 4). This is striking as flies are insects and scorpions are arachnids. He uses an insect image as a reaction to the arachnid's sting. He further extends the simile when he describes how the villagers "buzzed the Name of God" (line 5). This gives the reader an impression that he finds them an irritant. This impression is reinforced by the following line: "More candles, more lanterns, / More neighbours." (lines 14 and 15). This clearly shows his frustration as more and more peasants arrive with candles and lanterns but not doing much else to actively relieve the pain his mother is going through.
Another instance of the poet's uneasiness with the neighbours is evident when he describes how their candles and lanterns throw "giant scorpion shadows" (line 6). Since the scorpion has parted, the images on the walls have to be those of the neighbours - shaped like a scorpion. He seems to imply that they are more of a burden than help.
The poet effectively portrays a sense of desperation and helplessness on the part of his father because although he, the father, is a sceptic and rationalist, he tries "every curse and blessing" (line 17) to help his suffering wife.