DREPANOSIPHUM ACERINA. 
185 
Kaltenbacli likewise remarks that all the larvae of the 
second and following generations from May to October 
assume wings, and that the Aphis appears of three 
different tints, viz. yellow, green, or brown, according 
to the time of year. 
Aioteroihs oviparotis female. 
Long oval. Green, transparent. Antennae ringed 
with black. Eyes bright red. Vertex, thorax, a series 
of transverse bars on the dorsum, and certain irregular 
blotches on the sides, velvety brown or black. This 
sex differs much from the viviparous female in both, 
colour and form. 
It is not uncommon on the under side of the leaves 
of the sycamore just before they fall. 
The last three abdominal rings are remarkably 
drawn out and expanded into a kind of sac, into which 
the ova pass before deposition. Fertilization takes 
place within this sac, and the change becomes visible 
by the alteration of the egg from its original green 
colour to a fine brown, the last tint commencing at 
the posterior end of the egg. 
On account of its size and transparence, this species 
is well fitted for anatomical examination. Accord- 
ingly it was much employed by Balbiani in his investi- 
gations on the reproductive economy of Aphides, 
Drepanosiphum ACERINA, Walh. Plate XXXVII, 
figs. 1 — 3. 
Jphis acerinay Walk. 
Drepanosiphum acerisy Koch, 
Apterous viviparous female, 
Indies. Millimetres. 
Size of body 0*070 X 0*040 1 *77 X 1‘01. 
Length of antennse 0*100 2*54. 
„ cornicles 0*015 0*12. 
