Q [Januarj, 



^ NOTES ON SAWFLIES, CHIEFLY AS TO OVIPOSITION. 

 BY THE LATE T. A. CHAPMAN, M.D., F.R.S. 



The observations here noted were directed specially to the disposition 

 of their eggs made by the. several species in oviposition. Other points 

 Avere noted l>y the way ; some of them may be of value, but I am very 

 imperfectly acquainted with the Continental literature on the subject. 

 The Rev. F. ~D. Morice has kindly helped me in determining the nomen- 

 clature, etc. The species studied are : Fteronidea curtispina Tlioms., 

 P. hypoxantlius Forst., P. oUgospiliis Forst., Fontania j^iliserra 

 Thorns., and PriopTiorus tener Zadd. 



Fteronidea curtispina Thoms. 



I have met with larvae of this species for several years past, but tliis year 

 I succeeded iu getting some eggs laid. The larvae feed on the edges of sallow 

 leaves and very much resemble those of P. oligospilus in appearance and habits, 

 but they are of n paler green and at once distinguishable by tlie double white 

 dorsal band, the two portions separated by the dark and conspicuously pulsating 

 dorsal vessel. On looking for the eggs several days after suppl^qng the flies 

 with Osier, I could find none — a circumstance explained a day or two later as 

 due to my loukiug for them under the leaves, fancying they must be placed 

 similarly to those of P. hypoxaiithus ox oligospihis, whereas they were laid on 

 the upper side in a manner very like that of Ti-ichiosouia ; at this time they 

 were becoming conspicuous, owing to the growth of the eggs in their pockets. 

 Luckily a few more eggs were laid, showing how easily they coidd be over- 

 looked when recently deposited, even when one knew how to look for them*. 



When recently laid the eggs are difficult to see ; they are laid in a pocket 

 on the upper side of the leaf, and are obviously very thin and fiat, as their 

 ])Osition is not indicated by any elevation of the leaf cuticle over them ; there 

 is of course a slight elevation to be seen when critically looked for, and there 

 is, if not at once, very soon, a pale line round part of the egf:;, where air 

 fills the angle between the upper and lower faces of the pocket, held apart by 

 the margin of the egg, rounded no doubt, thin as the egg may be. These notes 

 are made from a separated twig in water; probably on the growing tree this 

 angle is filled by exuded sap. The natural appearance and colour of the cuticle 

 over the egg suggest that a certain trace of the parenchyma of the leaf is 

 attached to it. The egg, however, grows chiefly in thickness, so that when 

 mature, just before hatching,its cross-section, instead of being notfar from linear, 

 is nearly a circle, and the egg and pocket stand up on the surface of the leaf 

 very conspicuously. At this stage the pocket does not expand with the 

 growth of the egg, and the cuticle covering the egg draws apart so that a 

 portion of the egg is exposed. The newly laid egg is pear-shaped, as seen 

 through the upper cuticle of the leaf — about TS mm. long and 0-6 mm. at the 

 widest part; thickness not measured. As it grows it does not increase in 

 length, but becomes nearly O'S mm. in width and as much in thickness, losing 



* [Enslin in Ent. Mittheil. vi, 1917, p. 241, mentions that P. curtispina oviposits on the upper 

 side of the leaf, and figures a leaf with " pockets " and eggs in situ. — F. 1). M.] 



