Response to cecropia cocoons of Mus musculus and two species of Peromyscus
SummaryIn rural areas cocoons of overwintering Hyalophora cecropia spum close to the ground are opened and the pupae eaten by small mammals, but in urban areas, where cecropia populations are much larger, the cocoons are almost never opened by mammals. Peromyscus leucopus noveboracensis and P. maniculatus bairdii are abundant in rural areas, but are largely replaced by Mus musculus in urban areas. In laboratory experiments P. l. noveboracensis invariably opened cecropia cocoons and ate the pupae. P. m. bairdii were slower to open cecropia cocoons and two of twelve did not open one at all. M. musculus, on the other hand, never opened cecropia cocoons although they gnawed the silk and ate uncovered pupae. Cocoons opened in the laboratory by the two species of Peromyscus cannot be distinguished from each other or from cocoons opened in the field.
Differential Predation on Cocoons of Hyalophora Cecropia (Lepidoptera: Saturniidae) Spun on Shrubs and Trees
The cocoons of Hyalophora cecropia (L.) were found at various heights on the branches of trees or close to the ground on the stems of shurbs in urban environments in Champaign and Urbana, Illinois. Over 81% of the pupae in cocoons on shrubs survived the winter to emerge as adults. Less than 4% of the pupae in cocoons on trees survived, over 86% having been killed by birds, almost certainly woodpeckers. Cocoons on trees are exposed while those on shrubs are usually well hidden. We suggest that the differential destruction of pupae on trees may be a recent phenomenon caused by characteristics of the urban environment, and that it would be reasonable to look for a rapid selection against spinning on trees. See full-text article at JSTOR
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.