Long before we learn what the creature in "Tree-sitter" is, we know how it behaves: it sits, sways, dreams aloud and calls out. Dave Bonta holds back the name until the last stanza, and until then the poem refers only to "it." A small being settles in the speaker's "pool" and addresses the speaker as "Luna," "as if I / were its pale progenitor." Luna means moon, and it is also the name of a pale moth. A reasonable reading is that the speaker is cast as a moth-mother, or as some moon-like being, whom the larva takes for a parent. The poem never confirms this, and the uncertainty is part of its charm.
The imagery keeps blurring the line between animal, plant and fungus. The creature "swayed like a sapling," its dreams are "plush as truffles / fruiting in the dark," and later it has "one short root." The truffle comparison is the most original. Truffles are soft, hidden and grow underground, so the phrase suggests that the larva has a rich inner life that nobody can see. The speaker is the only witness to it.
The second stanza widens the scale and gets stranger. Other larvae "boiled in & out / like tiny, earth-bound storms, / chewing with a fury." The verb "boiled" makes a swarm into a liquid, and the "storms" make munching jaws into weather. Then the speaker's own kin arrive: "my cousins shook the mountain / when they came down." Suddenly the speaker belongs to a family large enough to move mountains, which gives the scene the feel of a fable or myth. Against all that noise, one larva "clung to me / with its naked forelimbs & howled." The word "naked" stresses how exposed it is, and "howled" gives a tiny body a huge voice. The phrase "strange familiar" sums up the poem's mood. A familiar is a companion creature, and the word also means something known, yet "strange" insists the speaker cannot fully know it.
The form is plain. There are three stanzas of seven lines each, in free verse with no rhyme, and the poem relies on sound and line breaks to hold it together. It opens with short, flat statements: "It sat down in my pool." The sibilance of "sat," "swayed" and "sapling" gives those first lines a gentle sway of their own. Later the ampersands in "boiled in & out" and "forelimbs & howled" give the writing a hurried, notebook-like feel. The line breaks do real work. "As if I" ends the line on the speaker's own pronoun, so the speaker's identity is something handed over by the larva. In the third stanza, "with which / it communicated" lets the sentence drift, much as the larva's signals "reach through the air somehow." That "somehow" is an honest admission that the speaker does not understand what is happening.
The last stanza changes the poem's tone. Description gives way to questions, and the past tense becomes clearly a memory. "Where did it go, that larva?" The word "larva" finally arrives, and in Latin it could also mean a ghost or a mask. Whether or not Bonta had that in mind, the effect is the same. The creature we have been watching is already slipping away. The final question, "Did it ever manage to spin / a real cocoon?", turns on the word "real." It is tender and a little anxious, as if the speaker feels responsible for a being that mistook them for a parent and cannot now check on its fate. The title, "Tree-sitter," may also recall people who live in trees to protect them. That is an inference, but it fits a poem about keeping watch over something fragile.
The poem matters because it takes the smallest kind of life seriously without turning it into a cute symbol. The larva gets dreams, language and a claim on the speaker, and the speaker gets only questions in return. Being trusted by something helpless carries a weight, and we may never find out whether we lived up to it. The poem lets that feeling stay unresolved.