Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 52. (Budapest 1960)

Móczár, L.: The loess wall of Tihany and the nesting of Odynerus spiricornis Spin. (Hymenoptera, Eumenidae)

3. of fig. 2). For the sake of a rapid desiccation, the wasp will not place the subsequent pills against, but rather far removed from, each other, and frequently in an opposite direction (fig. 2—6). Pills 1. and 2. were adjacent in 7 cases, but at least one pill away from each other in 11 cases. The same rate, with reference to pills 3—4. is 3 : 13 ; that of pills 5—6. is 1 : 5 ; that of pills 2—3. is 3:11; and finally that of pills 4—5. is 3:5. Therefore the wasp placed the pills beside each other in 12 cases, and removed them from each other in 35 cases. Nor docs the irregular depositing of the pills follow the principle that they should be immured into always the lowest portions. In several cases, the wasp developed the higher parts of the turret instead of filling in its chips. However, no great disproportionateness results, the final mouth of the turret and the height of its rim are of a relatively identical height. The building of the turret progresses at first rather rapidly, in the rate of the hollowing-out of the burrow in the wall. The intervals in the activities of the wasp are convenient also for the drying-out of the recently erected fresh portion. I could never observe a wet turret higher than 20 mm (Plate II, fig. 5—6). Especially those turrets will develop quickly which are not impeded bv a projecting ledge or another turret. These abstacles are obviated by the wasps by bending the turrets. Such curves and bends require a structure of an increased stability. The wasp will frequently paste the excavated material on the innerside of the turret and not on its upper rim (the small inner circles in fig. 2—6). By this, it thickens and solidifies the turret, daubing its surface at the same time, then smoothing it off into a cylindrical shape. The wall of the burrow within the loess wall is similarly cylindrical and smooth. There is no shiny coating in the Odynerus structures as in those of the Halictus species. In the first phase of the building work, — till the turret is ready — they generally use the excavated material for the erection of the turret or for its inner fortification. However, it happens sometimes that they let fall the mud pill from the rim of the turret or more frequently during a short flight around the circle of a small radius (fig. 3, 6 ; circles indicated by an arrow). The length of the turrets attain an average 72 mm on the basis of 45 whole turrets (the extreme values are 43—116 mm). The data for 1938 (L. Móczár 1939) were 60—70 mm (maximum 140 mm). The time required for the finishing of the turrets depends on the activity of the wasp, the composition of the substratum (harder or softer), the nearest vicinity of the turrets (a smooth surface or various kinds of obstacles), and last but not least on weather conditions. Odynerus Nr. 3. built a construction as long as its own body (half of it the burrow and half of it the turret) within one and a half hours in the forenoon. On the next day, it increased its nest in a similar rate or proportion during 3 hours (discounting its absence for two hours in two cases): developing it by 43 mm burrow-, that is, turretlength. On the whole therefore, it constructed a burrow of 63 mm (of which the turret measured 30 mm) in the hard, sedimentary layer, during 6 hours and 40 minutes in two days. Some other wasps (Nr. 9—14) constructed a body-length nest in two and a quarter hours. And wasp Nr. 18. built a nest of three times its own length late in the afternoon, during one and a half hours. On the day of observation, no other wasp erected a longer turret, attaining the above average 72 mm length. This might have been in connection with the proximity of the termination of the breeding period, but also with the fact that the wasps may partly increase the turrets by the excavating and building of the fresh cells ! Even if we take as an average the building of wasp Nr.