95 



Mr. F. Walker read the following 



Notes on Aphis Quercus, 



" Having lately taken a few specimens of the Aphis Quercus of Linneus, I beg 

 leave to offer to the Entomological Society a few notes on that species. It was first 

 discovered by Mr. Ingall, in 1847, on an oak at Dulwich ; Mr. Smee found it soon 

 afterwards at High Beach, in Epping Forest ; and about a month ago, when I hap- 

 pened to meet him, he told me that he had just observed it on an oak at St. George's 

 Hill, Weybridge. He kindly directed me to the spot, and after some search I found 

 the oak tree by a foot-path in the wood, and in the neighbourhood there were two 

 other oak trees also infested by the Aphis. The presence of the latter is detected by 

 the numbers of the black ant which come to feed on the honey, and whose multitudes 

 much add to the trouble of extracting the Aphis, for its body is so soft, and its rostrum 

 is buried so deeply in the bark, that it must be cut out of the tree carefully, in order 

 to avoid crushing it. I then wrote to Mr. Ingall, and asked him some questions 

 respecting the structure of the rostrum, and he with much kindness lent me all the 

 specimens which he had preserved in Canada balsam, fifty-five in number, and his 

 MS. notes, from which I have extracted nearly all the following observations. 



"The Male. 



"This is apterous, like the males of many 'other species of Aphis, and appears 

 about the beginning of October, and continues till November. It is less than one- 

 fourth of the size of the female, and about twice the size of the egg (which is large), 

 and has no appearance of any mouth either in the young or in the adult state. In 

 other species of Aphis the mouth has a like structure in both sexes. 



"The Winged Female. 

 " This lives early in the year, and seems to be scarce. It does not possess the long 

 rostrum which distinguishes the following form, and is very different from it in 

 appearance. 



"The Wingless Female 

 has a rostrum which is more than twice the length of the body, and in the young 

 insect is more than four times the length of the body. It seems to be quite distinct 

 from the true mouth, which possesses three extremely slender set£e (the middle one 

 double) ; these are received into the groove of the rostrum or tube, and rather exceed 

 it in length. The rostrum is fitted into a ' sac at the base of the lower lip, which sac 

 probably extends nearly the length of the body ;' it can be folded? and is often con- 

 tracted to half its usual length, and more rarely to one-fourth of its usual length, and 

 may be seen retracted within the body to the base of the fore legs, or to the base of 

 the hind legs, or even to the tip of the abdomen. The joints, also, of the rostrum can 

 be withdrawn one within another, like the parts of a telescope, and the whole appara- 

 ratus is peculiarly adapted for the extraction of the sap of the oak between the rugged 

 clefts of the bark. The eggs are deposited in October and November. 



" I will endeavour to make further observations on this species during next year, 

 and hope that in the meanwhile some person will kindly undertake to dissect it, in 

 order to ascertain fully the structure of the rostrum, and how it is received into the 

 body." 



