S. Mahunka szerk.: Folia Entomologica Hungarica 59. (Budapest, 1998)

15 June, 1996 Eight larvae, which were close to have completed larval development, were transferred to fresh elm-tree bark in a vial of the same size. Sap flow from elm-trees in the Halmi-erdő dramatically decreated (13 June) and stopped (15 June), but after rains it afreshed again by the 25th of June. The larvae of Periscelis are well adapted to these circumstances: they are able to suspend feeding for a long period of time. In that stage their life activities have almost stopped. However, these "dried-out" larvae revived by a single drop of water. Actually I put a tiny drop of water to the mouth opening of these larvar and they begin to move vividly within a minute. 25 June, 1996 One of the larvae died, while another one was dying, and altough others were still alive they did not pupate. 15 July, 1996 Four of the larvae were still living. The less developed ones died by that time. The evertable anal protuberance may play a role in maintaining osmotic equilibrium. I think so since the protubarances were at once everted in 1% sugar solution. The sugar (saccharose) is not a feedstuff component of the larvae: they withdraw their heads even in the weakest solution of saccharose. 17 August, 1996 Accident. Two of the three larvae, which were still living last evening, were drowned in the fresh elm-tree sap. Last evening they ate from the sap and they were not only revived but they became definitely thicker. However, the 10 mm deep sap (mixed with small bark particles) proved to be too short for breathing. The last living larva was put into a smaller vial. 15 September, 1996 The last larva died during the L3-P transformation between the 10th and 14th of September. Summarily, it is obvious that the larvae of Periscelis annulata require a well definable food, among special circumstances. This food is the fresh and not mucous sap of trees, which oozes out soaking the still hard bark of definite structure. I presume that this fresh sap is poor in microorganisms, at least so compared to the sites where Brachyopa or drosophilid larvae are living in sap flows. In lack of fresh sap, i. e. when - in summer - sap flow is reduced or stopped, they are sleeping. This sleep (dormantia, see Polgár and Darvas 1995) is suspended at anytime when water or even tree sap is reaching them. The water/sap is percepted by their mouth papillae: a drop of water placed locally on their body will not awaken them. The larvae involved in my trials were eggs in 1995. They hatched and they developed for a period of time (I presume these larvae developed for a period of time (I presume these larvae developed into the third larval instar in 1995). They overwintered as third instar larvae emerged from eggs laid in 1996: the first adults (males) emerged in the Péterhalmi-erdő on the 1 st of May. (The overwintering phase may also be the puparial stage, of course.) Altough our data are still incomplete, we think it probable, that in "good years" larvae, which overwintered, can develop into adults as early that the resulting adults may