368 ZOOLOGY 
is the first and only appearance of this sex in the life-history 
of the Phylloxera. The male is devoid of mouth and aliment- 
ary canal; it fertilises the female, which soon after lays a 
single fertilised egg, the so-called “winter ege.” This is 
deposited in some crevice or crack in the bark of the vine ; in 
the spring a “stock-mother” hatches out of this egg and makes 
her way to the young buds of the vine, and inserts her pro- 
boscis into the upper surface of a leaf. The irritation thus set 
up causes the formation of a hollow gall on the under surface 
of the leaf, which opens to the exterior on the upper surface. 
The stock-mother lays eggs, and her offspring—gallicola—give 
rise to new galls, but ultimately some of them descend to the 
eround, burrow beneath it, and attach themselves to the roots, 
and thus become radicola. 
The complicated life-history of this form may be expressed 
by the following table: 
Root-infesting form § (radicola) 
Root-infesting aay 2nd generation 
Root-infesting form, 3rd generation, etc. 
Winged form 2 
a egg Small egg 
Wingless female Male 
“A 
Winter egg 
Stock-mother 
Gall-producing form @ (gallicola) 
Gall-producing form 2, 2nd generation, ete. 
Root-infesting form 9 (radicola) 
Family CoccipDAk (Scale Insects, Bark Lice, Mealy Bugs).— 
The members of this group differ a good deal both in their life- 
history and in their structure, and very frequently the two sexes 
of the same species are markedly different in appearance and 
habits. The antennae are usually long, eight to eleven joints, and 
filiform ; the tarsus is two-jointed. The males alone amongst 
