248 THE ENTOMOLOGIST. 
used in the preservation of lepidopterous and other larve, 
namely, inflation by hot air. It must be stated, however, that 
the distinctive specific characters of Aphides are by no means 
sharply marked; their size, form, and colour so quickly change 
according to their degree of maturity, and they are so easily 
affected by the manner of living, viz., by the ever-changing 
meteorological or climatal conditions, or by the natural seasonal 
changes, by variation of food plant, and other surrounding 
circumstances. 
“The cause of this interest may be traced without difficulty to two 
principal facts. In the first place, the study of these creatures has 
presented to the embryologist questions for solution of the greatest 
importance. Phenomena connected with processes of reproduction occur, 
which, even now, some physiologists consider to be abnormal, and 
concerning the interpretation of which unqualified consent is by no means 
accorded. In the second place, the general uaturalist has found much to 
engage his earnest attention, whether he regards the varied life-history of 
the different species of Aphides, their curious habitations, the injuries they 
inflict on vegetation, or the defences they make against the host of insect 
foes which attack them on all sides,—attacks which keep within limits an 
extraordinary fecundity, which otherwise might bring famine into the 
districts they infest.” 
So says Mr. Buckton, and the life-history and metamorphosis 
of an Aphis is indeed extraordinary. Even now, these questions 
of reproduction, the extreme rarity of the males, the distinction 
of the perfect sexes, oviparism and viviparism, parthenogenesis 
and metagenesis, their migrations and extraordinary swarms, are 
far from being satisfactorily settled. The biology of so 
exceptional a group must be both interesting and instructive 
to all who are disposed to follow it out. I had intended to have 
given a sketch of ‘“‘the cycle of the compound individual,” but 
this article is already long; still before bringing it to a close, the 
various and beneficent Aphis destroyers must be referred to. — 
These natural limiters act in two ways, from without and from 
within. The devourers from without are the larve of the 
dipterous Syrphide (hovering flies), the neuropterous Hemerobiide . 
(golden-eye or lace-wing flies), and the coleopterous Coccinellide 
(ladybirds) ; these larvee, happily for vegetation, are all particularly 
voracious and particularly common, The larvee of certain Seymni 
also feed upon Aphides, uid Mr. J. W. Slater has recently proved 
