Aristaeus performs the ritual.
The story becomes exceptionally compressed here, as Aristaeus immediately goes to fulfill his mother’s orders. He sets up the altars, selects the sacrificial animals, exactly as commanded. After nine days Aristaeus returns to the grove and witnesses a wondrous sight: huge swarms of bees have emerged from the cattle and hang from the trees.
548 haud mora: supply erat. Vergil also does not delay: he does not return Cyrene to her underwater lair or Aristaeus to Arcadia. Aristaeus is now instantaneously ready to perform the works of expiation. Notice, too, that the rites that Cyrene has spelled out to Aristaeus are nowhere articulated by Proteus—she appears to understand what must be done because she is a divinity herself.
548 facessit: from facessō, the intensive (or meditative) form of faciō. Verbs that end in –essō show eagerness or activity (AG 263.2b).
550 praestantī corpore: as in line 538. Notice how the language of lines 550-553 repeats almost verbatim lines 538, 540, 544-546. While this imitates the repetition in rituals found in Homeric epics, it also appears that Aristaeus wants to get this right!
551 intactā…cervice: as in line 540.
552 Aurōra: as in line 544.
553 īnferiās Orpheī: as in line 545.
554 hīc: adverb.
554 vērō: adverb, “indeed,” used to emphasize the demonstrative hīc (see OLD vero 5)
554 dictū: supine in the ablative (AG 510); take closely with mīrābile.
554 mōnstrum: “wonder” or “an amazing occurrence.”
555 aspiciunt: the subject is Aristaeus and whatever people are nearby, helping him with the ritual.
555 boum: genitive plural of bōs, as in line 543 (AG 79).
555 tōtō: modifies uterō in line 556; an ablative of place where without a preposition, as is common in poetry (AG 429.4).
556-558 strīdere…efferuere…trahī…confluere…dēmittere: a series of verbs in indirect statement, which describe the mōnstrum: they see an amazing event, that the bees buzz, break out, depart in clouds from the carcasses, etc.
556 apēs: the subject accusative for these verbs.
556 ruptīs…costīs: ablative of place from where (AG 428g).
557 immēnsās…nubēs: an appositive of the subject accusative, apēs; the bees are drawn out of the carcass in great clouds, cluster together and then hang from branches. These are swarming bees, as we first encountered at line 60.
557 arbore summā: ablative of place where without a preposition, as is common in poetry (AG 429.4).
558 lentīs…ramīs: ablative of place from where (AG 428g). The swarm weighs down the pliant bough.
558 ūvam: that is, a cluster of bees that looks like a bunch of grapes.