A comparison, by sweep sampling, of the arthropod fauna of secondary vegetation in Michigan, England and Costa Rica

Abstract

1. Six 8oo-sweep samples of English and Michigan ("old field") secondary vegetation arthropods are compared with Costa Rican samples taken in the same way. 2. Parasitic Hymenoptera and spiders accounted for a larger proportion of the arthropod fauna in the mid-latitude than the tropical samples. 3. In one English field, the seasonal change in insect numbers was 88% of that recorded over all the seasonal and elevational changes examined in Costa Rica. Furthermore, the difference in the total dry weights of the arthropod fauna between December and July was similar to the difference found between the wet and dry seasons in tropical secondary vegetation (also similar to the difference between day and night values during the dry season). 4. Aphids and Psyllidae were far more abundant in the English site than in the Costa Rican mainland sites. s. In mid-summer, the English field had far more arthropods in it than did any of the tropical sites sampled.