THE EGG-LAYING OK PHYMATOCERA ATERRIMA, KLUCi. 145 



The Egg=laying of Phymatocera aterrima, Klug. {With tno platrs.) 



By T. A. CHAPMAN, M.D. 

 ]\Ir. L. E. Adams, having discovered in his garden a colony of 

 P/iijiiiatocera aterrima, Khig., afforded me the opportunity of observing 

 its process of ovipositing. This is the species that Mr. Morice observed, 

 and gave so interesting an account of in his Presidential address to the 

 Entomological Society in January, 1912. As such records are not 

 numerous, it is not undesirable that further observations should be 

 reported in confirmation and extension of those already made. It 

 seems also expedient to compare the operation of egg-laying as carried 

 out by Pkijiiuitorera with the procedure of Trifhiosoina, which I 

 observed two years ago {Trans. Ent. Soc, 1914, p. 173). 



Without regarding it as necessary to adopt strict priority in the 

 naming of anatomical structures and various parts of insects, it is well 

 to do so as far as possible. 



"Mr. Morice has been kind enough to give me the result of his 

 enquiries as to the names of the several structures used by sawHies in 

 oviposition given by the earliest authorities. Linn;T3us recognising, that 

 these parts are, as has since been shown, homologous throughout the 

 Hymenoptera, called the piercing organ, as a whole, aculeiis. 



Latreille apparently restricted acuh'ii:< to the ovipositor of the 

 Anileata, giving the name terehra to that of sawflies (and others). 



Recognising that terebra is in one sense a partial synonyiii of 

 aculetis, we may accept it for the ovipositor of sawliies, since though 

 we might call it an acideus, we could not very well call it a sting. The 

 terebra consists of two plates, each of two parts, which in the vernacu- 

 lar are now known as " saws " and " supports." The Latin names for 

 these as given by Kirby (1802 '?) are, for the supports, vaijina, for the 

 saws, s/iiciila, and for the saw-sheath into which the terebra retires 

 when at rest, the valrae. Mr. Morice discards .y<-aljielli(iii as synony- 

 mous with ariileiis (and terebra). 



I'/iijiiititocera lays in stems of ('onrallaria which are still growing 

 and succulent, just as Trichiosonia lays in the young growing leaves of 

 Sali.r. It resembles it in another peculiarity, ri:., that its operations 

 are carried out by separating the cuticle from the underlying tissues, 

 and not by digging into the latter. The same process is followed by 

 other species whose eggs I have examined after they were laid, though 

 Avithout having seen the actual laying. For example this was the case 

 ■with a fly, which, if I remember rightly, Mr. Morice told me was 

 E)iil>lnjtns (jrassiilariae, of which, some years ago, I bred continuously 

 several generations, on violet. The larva was black with white dots, 

 quite unlike that described as that of E. t/nmsiilariae in Cameron's 

 I'/ii/toij/iaf/ons I li/inenoptera. This insect is of course unrelated to 

 Xeniatiis ribesii, the gooseberry pest. The eggs are laid singly in the 

 upper surface of leaves of dog-viol(;t, and grow somewhat after they are 

 laid. 



A peculiarity in the laying of I'/ii/iiiatdcera depends on the circum- 

 stance that the growing stems of Conrallaria, in which the eggs are 

 laid, are small, 2mm., 2-5mm. to 8mm. in diameter, larger (and 

 older) stems are not, so far as my few observations go, affected by the 

 insect, the largest I have seen was under 4mm. in diameter. The 

 cutting is done transversely to the stem, and so, to accom4iio^te.it^lf 

 July-August, 1915. X'\?^^'**'^ ''f«^'///f-J;> 



JUL 30 1815 



