The hermaphroditic pond snail Lymnaea stagnalis has long been used as a laboratory model for the study of neurohormonal regulation of reproduction and growth. In parallel, the allocation of resources towards reproduction, growth and maintenance has been studied as a means to understand the hermaphroditeâs life-history. To gain insight into the seasonal changes of resource allocation towards female and male function, as well as towards body growth we have collected snails in a Dutch ditch for over two years on a monthly basis. The weights of the prostate gland and albumen gland were determined as well as body size and (dry) weight. Animals that survive the winter months (December to March) copulate at the start of spring. A few weeks later, egg masses appear from which the next generation hatches, grows and matures in about two months. As last yearâs generation dies off, the new one becomes sexually active. This means that there is little opportunity for copulation between generations. The last egg masses, laid by the new generation, are laid around the autumnal equinox. Towards summer, both generations show a decrease in dry weight density suggesting that the snails apply the acquired energy to reproductive output instead of storing it. The results obtained in the ditch are compared with laboratory studies on the physiology of reproduction, as well as on sex allocation.