Coloration and Development of Insects. 77 



their having had any connection with males, and from 

 these eggs I bred only males. A few years ago T got an 

 unfertilised ? of Nematus miliarls, Pz. (viridis Htg,), to 

 lay eggs, but the larvixj which they yielded, unfortunately 

 died in the cocoons during the winter.* Last year I was 

 more successful with this species, and succeeded in rearing 

 the . images from unfertilised eggs : they were all males. 

 N. miliaris, I may remark, has the males — if not as 

 abundant as the other sex — tolerably numerous. I was 

 also fortunate enough to get Strongylogaster cingidatus 

 Fab., Phyllotoma nemorata, Fall., and Hemichroa rvfa, 

 Pz., to lay unfertilised eggs, which yielded larvse, but 

 unfortunately they all died very young. The ^ of S. 

 clngidatus is knoAvn, but is certainly very rare ; while the 

 males of the other two are quite unknown, although they 

 are very common species and have been often bred. I 

 experimented with several other species, but the result was 

 altogether negative : they would not lay ; nor indeed 

 would all the individuals I had of the species I have 

 mentioned. 



Mr. J. E. Fletcher, of Worcester, has kindly communi- 

 cated to me the results of some experiments he made last 

 year on the same subject, f He got the common gall- 

 making species, Nematus gallicola (Vallisneri) to oviposit, 

 but the gall did not come to maturity, owing apparently to 

 the plant being small and weak. Mr. Fletcher was more 

 fortunate w'ith Nematus curtispina, Thoms., and N. 

 palliatus, Thoms., having managed to rear from unfer- 

 tilised eggs 21 c? and 1 ? from the former, and 2 S from 

 the latter species. That a ? should appear as with 

 N, curtispina is certainly very exceptional, but I have 

 no doubt of the correctness of Mr. Fletcher's observations ; 

 although it is quite possible that the egg may have been 

 brought in with the food-plant, or a pupa may have been 

 put in by mistake, as happened to Yon Sicbold when con- 

 ducting his experiments. Both species are closely related 

 to N. miliaris, but both are good species. 



From the above remarks it Avill be observed that the 

 experiments were onlj^ completely successful with those 

 species which have the males tolerably common ; while 

 they have only shown that those species which have the 

 males exceptionally rare, or altogether unknown, are 

 capable of laying fertile eggs, but without telling us if they 



* Scot. Nat., iv., 157. 



t Seo also Ent. M. Mag., May, 1880, p. 2G9. 



