Abstract. 1. In studies of insect‐host plant interaction it is often suggested that insects preferentially colonize host plants (or sites within plants) on which their fitness is maximized (a positive covariance of preference and performance). This suggestion stems from the assumption that natural selection has driven the system toward optimal use of resources. 2. Our study of the galling aphid Smynthurodes betae Westw. demonstrates that the distribution of galls on leaves is not due to preference, and can be altered by manipulating the aphid arrival time or the shoot growth rate. 3. We found no correlation between gall density and performance (aphid clone size) at different positions along the shoot. 4. Because leaves on the growing shoot are not equally responsive to aphid stimulation, the colonizers have no choice but to settle on leaves that are at the right stage when they arrive. 5. S.betae colonizers did not discriminate between shoots of their host and a congeneric non‐host, on which their fitness is invariably zero. 6. Synchronization between galler and host plant phenologies seems to be the key to the observed distribution of galls on the tree. The data give no support to the preference‐performance hypothesis.

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The Palmaz-Schatz coronary stent is used frequently to reduce the rate of restenosis of balloon angioplasty in saphenous vein grafts. In many European centers, the stent, manually crimped on a balloon, is advanced across the stenosis without a protective sheath. This report describes a patient in whom an attempt to deploy a stent in the orifice of a saphenous vein graft was complicated by dislodgement of the unexpanded stent from the balloon. The unexpanded stent caused immediate occlusion of the vein graft and severe ischemic symptoms. The stent was retrieved by inflation of another balloon in the graft, distal to the stent, pulling the balloon toward the guiding catheter, and then withdrawing the whole system.

In most gall-forming aphids, only the fundatrix is able to induce a gall on the host plant. In Smynthurodes betae Westw. (and a few other species), Fz descendants emerge from the mother gall and induce their own, morphologically different galls. This constitutes an added complexity to the already very complex life cycle of gall-forming aphids.We investigated the ecology of S. betae on marked trees and shoots at four sites in Israel. Gall initiation, gall distribution and density, and temporal changes in clone size within the galls were investigated during two consecutive years. We discuss the possibility that the two-gall life cycle evolved from the typical one-gall system of most gall aphids, and the possible selective advantage of this added complexity in the lifehistory strategy of gall aphids. Although the total reproductive output orS. betae is not higher than in related species with a single gall per life cycle, there seems to be an advantage in the subdivision of each aphid clone into several galls, thus reducing the risk of the accidental extinction of the clone (genotype) by environmental factors, including parasites and predators.

In an ecological investigation of the gall-forming aphid, Smynthurodes betae Westw., we discovered that more than 20 % of the fundatrix galls were parasitized by Monoctonia pistaciaecola Stary (Aphidiidae). This is a new host record for this parasitoid. A Pteromalid hyper-parasite was identified as Pachyneuron ? leucopiscida Mani. Ecological information on the parasitoid is provided, and the low frequency of parasitoids known from gall-forming aphids, compared with freeliving ones, is discussed. KEY-WORDS : Gall-forming aphid, Fordinae, parasitoid, ecology.The morphological variation and ecology of four species of Fordinae (Homoptera, Aphidoidea), forming galls on species of Pistacia (Anacardiaceae) were investigated in our laboratory in the past 20