薔薇莖蜂の觀察 (II)

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This Rose-stem sawlly damages the rose-trces in the spring, prior to the oviposition the female saws several places in a shoot of the rosetree, which had just come out, with its saw-like ovipositor thereby causing the tip of the shoot to droop, die and fall off. In Tokyo, it has one generation in a year. The adult emerges and appears during late April to early May and immediately followed by mating and oviposition. The eggs hatch in about a week. The larvae mature in the middle of June and spin their cocoons and winters. They pupate in the middle of April of the following year and the pupae emerge a dozen days after pupation. Although the respective periods of the egg, the larval and the pupal are not elearly known, yet the whole period, i.e. a period of time between the oviposition and the emergence is 339 to 352 days. The emergence stage of the adult is prior or subsequent to April 20, but when it was transported to Hirosaki (N. Lat., 40.6°), Aomori Prefecture, north of Tokyo (N. Lat., 35.7°) in April and kept there, it emerged as late as before or after the 10th of May. The life of the adult is 1 to 4 days according to 28 examples in which no water or food was given. Respecting the mating habits, Mr. Kwo-Mo Ho clarified it in his "Studies on the Rose-borer, Neosyrista similis (MOCOSARY)" in Bul. Sc. Fak. Ter., Kyusu Imp. Univ., vol.7, No.2, pp.185∿210 (1936), so it is purposely omitted here. Oviposition period or the period in which this sawfly damages the rose-trees, is from late in April to the middle of May, and the crest of oviposition is the first part of May. The eggs are generally laid between 10 : a.m. and 3 : p.m. when the ray of the sun is strong. The female acts peculiarly when it oviposits ; it bores a number of longitudinal holes on a shoot, usually numbering 2 to 5, and the holes appear like they are arranged spirally. The incision of the ovipositor beneath the epidermis of this part is inverted letter V in shape and is very distinet. The egg is deposited in a small cavity made on the vertex of the crown of the inverted letter V, but generally a single egg is laid on each shoot and the egg appears to be always deposited only in a incision in the highest portion of the shoot. When the larva hatehes, it devours between immediately beneath the epidermis and the material, bores its way into the pith gradually and advances upward. Later, it changes its course ; descends to the base and advances from the incised portion to still lower part where it makes a cavity, spins its cocoon and pupates by turning upward. The damged shoot dies and falls off near the upper end of the pupa cell. As natural onemics of this sawfly, the following four species of larval parasite were obtained : Exeristes sp., Cryptus sp., Pimpla sp., and Eupclmes sp. To control the present species, (1) the adult should be caught and destroyed and (2) the damaged shoots must be clipped off. Further, Naphtbaline spray was applied as a preventive of oviposition, but it has not as yet shown sntisfactory result. Actual results of control : The author has endeavoured to clip off the damaged shoots of rose-trees in his own rose garden in Tokyo since 1934 and the appearance of this Cephid wasp diminished in number every year, and linally he has succceded in getting rid of it. Needless to say, in a large area or if there are many rose gardens scattered in the neighbourhood, it will be almost impossible to obtain such a good result as noted above, but the author believes that the clipping off the damaged shoots could prevent the injury of this wasp to a remarkable degree.
1939-01-31

薔薇莖蜂の觀察 (II)

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