Suetonius remarks that he fell into great poverty in his old age, and was supported by the historian Clodius Licinus. Hyginus was a voluminous author: his works included topographical and biographical treatises, commentaries on Helvius Cinna and the poems of Virgil, and disquisitions on agriculture and bee-keeping. All these are lost.
Under the name of Hyginus there are extant what are probably two sets of school notes abbreviating his treatises on mythology; one is a collection of Fabulae ("stories"), the other a "Poetical Astronomy".
Fabulae consists of some three hundred very brief and plainly, even crudely told myths and celestial genealogies, valuable for the use made by an author characterized by his modern editor as adulescentem imperitum, semidoctum, stultum of the works of Greek writers of tragedy that are now lost. This school-boy compilation represents in primitive form what every educated Roman in the age of the Antonines was expected to know of Greek myth, at the simplest level. The Fabulae are a mine of information today, when so many more nuanced versions of the myths have been lost. In fact the text of Fabulae was all but lost: a single surviving manuscript from the abbey of Freising, in a Beneventan script datable c. 900, formed the material for the first printed edition, negligently and uncritically transcribed by Jacob Micyllus, 1535, who may have supplied it with the title we know it by. In the course of printing, following the usual practice, by which the manuscripts printed in the fifteenth and sixteenth centuries have rarely survived their treatment at the printshop, the manuscript was pulled apart, and only two small fragments of it have turned up, significantly as stiffening in book bindings. Another fragmentary text, dating from the fifth century is in the Vatican Library. (Major 2002)
De Astronomia was first published, with accompanying figures, by Erhard Ratdolt in Venice, 1482, under the title Clarissimi uiri Hyginii Poeticon astronomicon opus utilissimum This "Poetic astronomy by the most renowned Hyginus, a most useful work," lists the stars in each constellation, but chiefly tells the myths connected with the constellations, in versions that are chiefly based on Catasterismi, a work that was traditionally attributed to Eratosthenes.
Both works are abridgments, and the style and level of Latin competence and the elementary mistakes (especially in the rendering of the Greek originals) are held to prove that they cannot have been the work of so distinguished a scholar as G. Julius Hyginus. It is suggested that these treatises are an abridgment made in the latter half of the second century of the Genealogiae of Hyginus by an unknown adapter, who added a complete treatise on mythology.