Remarkable, however biologically unknown sawfly Craesus latipes (Villaret) (Hymenoptera, Tenthredinidae)

Abstract

URBAN, J.: Remarcable, however biologically unknown sawfl y Craesus latipes (Villaret) (Hymenoptera, Tenthredinidae). Acta univ. agric. et silvic. Mendel. Brun., 2012, LX, No. 3, pp. 179-198 In 2009 to 2011, a rather frequent occurrence of Craesus latipes (Vill.) was noted on Betula pendula Roth. in the Brno region. Part of the sawfl y population showed bivoltine and part univoltine development. At the bivoltine development, imagoes occurred for the fi rst time in the second half of May and at the beginning of June, for the second time in August. At the univoltine development, imagoes fl ew in the second half of June and in the fi rst half of July. Females lay eggs into longitudinal slits in veins on the abaxial face of leaves. During several days (in the laboratory already during fi rst three days) they lay 91 as many as 133 eggs on seven to ten leaves. They die one to three days a er oviposition. The embryonal development takes six to seven (in the laboratory four to fi ve) days. Male larvae eat for two weeks (in the laboratory 12 days) and show fi ve instars. Female larvae eat for three weeks (in the laboratory 16 days) and show six instars. Male larvae destroyed in captivity on average 19.8 cm 2 (female 60.0 cm 2 ) leaves of B. pendula. Larvae of the bivoltine subpopulation occurred on trees for the fi rst time at the end of May and in June, for the second time in the second half of August and in the fi rst half of September. Larvae of the univoltine subpopulation occurred from the second decade of June till the end of August, exceptionally even later. Eating larvae could be noted locally and in small numbers for nearly the whole growing season 1 .