J. H. MERRILL 145 



wood. If one would rear the larva of a Pwipla persuasoria, one 

 must give it the remains of the same larva for nourishment in 

 which it was hatched." 



Riley says ^•^ that Ratzeburg states that both Nordlinger and 

 himself raised Rhyssa persuasoria from Sirex spectrum, but does 

 not give any details of his observations nor does he state that 

 the parasite in ovipositing pierces the wood-boring grub. 



The subject of the habits of Rhyssa is by no means a clear 

 one, and it awaits some worker who will be fortunate enough 

 to observe its complete life history. 



The genus Rhyssa Gravenhorst, has its clypeus medially 

 lengthened or unidentate and its abdominal segments rounded 

 at the apices. The sternal plate of the second abdominal 

 segment is not fused with the pleura. The projections of the 

 sternal plates on either side of the mid-ventral groove are placed 

 about mid-way between the base and apex of each segment. 

 The sternal plate of the second abdominal segment is composed 

 almost wholly of chitin. The ovipositors of Rhyssa are but 

 little longer than the body, consequently they do not need the 

 membrane which is used by Megarhyssa in forcing its long ovi- 

 positor into the wood. 



Since the above was written an article has appeared on the 

 habits of oviposition by Rhyssa by L. N. G. Ramsay,^-'' as follows: 



"The remarkable insects of the genus Rhyssa have for long 

 been known to prey on the wood-boring larvae of Siricidae, 

 introducing their eggs into the tunnels of the latter by means of 

 their enormously elongated ovipositor. The ovipositor is some- 

 times even found sticking in a »S/re.r-infested log (as, for example, 

 the specimens exhibited in the insect gallery at South Kensing- 

 ton), but, I understand, the manner in which the insect contrives 

 to insert this unwieldy appliance into the tree-trunk has not 

 hitherto been fully described. I hope, therefore, that the follow- 

 ing account may be of interest to entomologists. 



"The event described was witnessed in the summer of 1909, 

 while I was staying in the southern part of the Black Forest, 

 to the west of the Wehratal. On the afternoon of August 29th, 



" Insect Life, i, 1888-89, p. 1G9. 



15 The Entomologist, xlvii, p. 20, f. U, (1914). 



TRANS. AM. ENT. SOC, XLI. 



