The poem begins with a brutal piece of nature: a wasp seizes a locust, paralyzes it, and lays eggs inside its still-living body. The larvae then eat the locust from within, and new wasps crawl out of its shell. The speaker describes this in a flat, almost clinical way, but the repeated line "the screams go on and on" keeps the locust's agony in our ears.
In the last stanza, the poem turns on the reader. Screams "crawl under your skin" and "eat you alive," just as the larvae eat the locust. New screams "cry out your mouth," like the new wasps emerging. The suggestion is that pain, once suffered, gets passed on and reproduces itself. The poem doesn't say what kind of pain, which lets it apply to many kinds of suffering. The mood is dark, claustrophobic and relentless. Repeated phrases like "the cycle repeats itself" make escape feel impossible.