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.本数据集包含两类数据： 1. 潮间带泥螺的体长及扁形虫寄生虫（flatworm parasite）感染状态； 2. 核桃实蝇雌虫的产卵穿刺行为相关数据：核桃实蝇雌虫可通过产卵器（ovipositor）刺破核桃果皮产卵，无法完成该穿刺行为的个体，会将卵扎堆产在其他雌虫钻出的孔洞中。本次实验共记录了56只不同体型的核桃实蝇的穿刺成功与失败情况，实蝇体型通过与整体体型相关性良好的翅脉指标进行测量。供试雌虫分为两组处理条件：一组为100%石蜡构成的硬质表面，另一组为75%石蜡与25%地蜡（ceresin）混合而成的软质表面。