1. The life history of wood feeders was modelled in order to explain the multiseasonality of development and the great variability of adult size in this group.
2. The model was parameterised with experimental bioenergetic and reproductive data for the xylem feeder Aredolpona rubra (Coleoptera: Cerambycidae).
3. The length of the developmental period, which together with food quality directly determines adult size and indirectly determines the number of eggs laid, was optimised.
4. The results show that multi-seasonal larval development maximises fitness under conditions of low food quality, relatively low predation pressure, and the presence of hostile periods during the year.
5. The variability of the number of seasons needed to complete development within a wood-feeder population is a consequence of development time optimisation and the unavoidable extension of the egg-laying period. These insects have an evolutionary dilemma: to eclose late in a given season at smaller size, bringing about low egg production and low offspring value, or to grow bigger to the next season, jeopardising their lives.
6. The results of the model predict wood-feeder developmental patterns that depend on the tree tissue inhabited.