snail and walnut fly data for logistic regression

Two datasets: 1. Mud snails in the intertidal zone are size and flatworm parasite infection status. 2. Female walnut flies lay their eggs walnuts by punturing the surface with their ovispositors. Females who cannot do this end up crowding their eggs in holes that other females make. Puncture failure or success for walnut flies of different sizes were recorded for 56 female walnut flies. Fly size was measured using a wing vein that correlates well with overall walnut fly size. The females were subjected to two conditions: a hard surface consisting of 100\% paraffin wax or a softer surface consisting of 75\% paraffin:25\% ceresin mixture.