782 RECORD OF CURRENT RESEARCHES RELATING TO 



comes the difficulty, that we know that the females die down after 

 having taken steps for the continuance of the race ; and again, what 

 have become of the numerous females developed in May, if it is 

 really true that the presence of the males is necessary for the forma- 

 tion of ova capable of development ? " They are mothers, and fertile 

 mothers, without having known the male." The generation in July 

 is therefore a true case of parthenogenesis. The results of these ova 

 are male and female, and the members of the former sex are in greater 

 abundance. Excepting the Aphides, this would appear to be the first 

 well-authenticated case of the alternate development of fertilized and 

 of non-fertilized ova among the Insecta ; the cases of Lepidoptera 

 which might be brought to bear upon the point are sporadic and 

 accidental. 



The author concludes with a notice of a parasite on E. sexcindus, 

 which is the larva of Myiochjtes subdipterus, a coleopteron with 

 greatly reduced elytra. As soon as the larva of Halictus has 

 swallowed its honey, it is devoured by Myiodytes ; as to the depo- 

 sition of the ova of this last, the author has at present nothing to 

 communicate. 



Galls produced by Aphides.* — In this paper M. Courchet deals 

 with the principal galls produced by aphides, from the trijile point 

 of view of their development, their morphological value, and their 

 structure. 



He abstains from discussing the action that the puncture exercises 

 on the vegetable tissues ; but he points out that if mechanical influence 

 could take any part whatever in the formation of galls it would cer- 

 tainly be in those of the aphides, the insect being always alive and 

 active in the heart of the new tissues. Further, the action of the 

 animal poison, to which, according to M. Lacaze-Duthiers and others 

 is attributed the production of the galls, is not absolutely comparable 

 to that of a virus on animal tissues ; the latter has no need to be 

 inoculated and incessantly renewed to give rise to the production of 

 special phenomena, whilst M. Courchet has always observed that the 

 galls (of aphides), which for any cause have been abandoned by their 

 inhabitants, are arrested in their growth. 



M. Courchet passes in review the galls of the Terebinth, the 

 Lentisk, the Black Poplar, and the Elm, dwelling particularly on 

 the first three, which are the most interesting and the least studied. 



Of the Terebinth, five galls are described : horn galls (galle en 

 corne), produced by Pempliigus cornicularius, and utricular galls by 

 P. utricularius, both formed at the expense of the tissues of the 

 median nervure. The three others are formed by the lamina of the 

 leaf folded in different ways, and are the production of P. j^allidus, 

 P.follicularius, and P. semilunarius. 



On the Lentisk is found one gall, produced by an Aploneura, and 

 which is similar to those of P. pallidus and P. follicularius. 



The Black Poplar has six galls ; one formed at the expense of the 

 tissues of a branch, the others being of a foliar nature. They are 



* ' Rev. Sci. Nat.,' i. (1880) pp. 533-41. 



