1881.] Entomology. 819 
light brown: On the third day a luxuriant growth of fungus gen- 
erally develops in the vessel containing the liquid, and its efficacy 
is then considerably lessened. 
5. Lhe Tea or Decoction—Professor E. W. Hilgard of Berkeley, 
Cal., is the only one who has experimented with Pyrethrum in 
this form and expresses himself most favorably as to the result. 
He says: 
“TI think, from my experiments, that the fea or infusion, prepared from the flow- 
ers (which need not be ground up for the purpose) is the most convenient and effica- 
cious form of using this insecticide in the open air; provided that it is zsed at times 
when the water will not evaporate too rapidly, and that it is applied, not by pouring 
over In a stream, or even in drops, but z2 the form of a j , , 
Jine holes in its rose. In this case, the fluid will reach the insect despite of its 
water-shedding surfaces, hairs, etc., and stay long enough to kill. Thus applied, I 
have found it to be efficient even against the armored scale-bug of the orange and 
lemon, which falls off in the course of two or three days after the application, while 
most tender growth, it is preferable on that score alone; and in the future it can 
hardly fail also to be the cheaper of the two, This is the more likely, as the tea 
made of the leaves and stems has similar, although considerably weaker, effects ; 
and if the farmer or fruit grower were to grow the plants, he would save all the ex- 
pense of harvesting and grinding the flower-heads, by simply using the header, cur- 
ves woulc making 
; ly bo 
water, but then simply covered over closely, so as to allow of as little evaporation 
as possible. The details of its most economical and effectual use on the large scale 
remains, of course, to be worked out by practice.” 
The method of applying Pyrethrum in either of the three last- 
mentioned forms is evidently far more economical in the open 
eld and on a large scale than the application of the dry powder, 
and, moreover, gives us more chance of reaching every insect liv- 
mg upon the plant to which the fluid is applied. The relative 
merits of the three methods can be established only by future ex- 
perience, : 
Micration oF PLant LIcE FROM ONE PLANT TO ANOTHER —M. - 
J. Lichtenstein of Montpellier, France, whose important entomo- 
logical writings are known here as well as in his own country, 
has been appointed by his Government to especially study all 
questions relating to the habits of the Aphidide. M. Lichtenstein 
as lor some years fully believed that most of our Aphids, and 
especially the gall-making Pemphigini, habitually migrate, in the 
winged, parthenogenic, female form, from one plant to another, and 
that the species must necessarily inhabit two different plants before 
it passes through its full cycle of development. That it is the rule 
for most of the insects of this family to so migrate is evident from 
"the fact, patent to all who have observed them, that there is a pe- 
tiod in mid-summer when most of the species abandon the plants 
which they so seriously affect in spring and early summer. This 
‘sappearance, emphasized already in 1829, hy Joshua Major, in 
