J. H. MERRILL 147 



Megarhijssa) in the act of oviposition, and states that in both 

 these genera the ovipositor is ''brought into use by being bent 

 on itself over the back of the insect, so as to bring the tip ver- 

 tically clown onto the wood, through which it is then forced by 

 a series of efforts; the sheaths do not enter the wood." 



It is evident that this description does not tally with the 

 foregoing observations on Rhyssa. The insect figured by Sharp 

 follow^s his statements in having its long ovipositor bent on itself, 

 out of its normal and approximately straight form, into an almost 

 complete circle. From purely physical considerations, is it not 

 a little difficult to understand how a non-muscular structure 

 could be curved at will in this way? The possibility suggests 

 itself to the present writer that the insect there figured, after 

 having inserted its ovipositor in the manner described in this 

 note for Rhyssa, may have pivoted its body through an angle 

 of 180° around the flexible fixed ovipositor, in its efforts to thrust 

 the latter into an unusually resistant piece of wood. This might 

 easily happen through the insect's shifting its feet again and 

 again to obtain a better purchase, and would explain the whole 

 matter very simply, as the ovipositor in such a case would natu- 

 rally assume the position figured. 



There can be no doubt at all that Mr. Ramsay's notes refer 

 to R. persuasoria (Linnaeus), which has an extremely wide dis- 

 tribution through Europe to Canada and the United States in 

 the West, and the Himalayas in the East, since it is to the best 

 of my knowledge the only species attacking phytophagous larvae. 

 R, approximator (Fabricius), is said by Holmgren to attack 

 Xyphydria prolongata, which feeds in oaks; and there are several 

 interesting accounts of the American species' economy ^^ and Har- 

 rington has^^ put on record "The Nuptials of Thalessa." jMr. 

 Ramsay appears to take it for granted that these insects bore 

 for themselves an egg-passage through the solid wood; but it is 

 by no means proved that they do not oftener introduce them 

 along the tunnel of the host larva. ^^ 



" Canad. Entom., xi, 1879, p. 15 etc. 



18 L. c. xLx, p. 206. 



19 Cf. Morley, Ichn. Brit., iii, p. 25, and Revision Ichn. Brit. Mus. ii, p. 10 



TRANS. AM. ENT. SOC, XLI. 



