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form. In Illinois this louse has been found on Easter lily, calla 
lily, maidenhair fern ( Adiantum hybridum and A. spp.), and Vinca. 
A dull-colored mottled plant-louse, Rhopalosiphum ( ?) nymphcece 
Linn.*, is often common in greenhouses. I have found it there 
on Philotria canadensis and calla lily, and it is sometimes a troub¬ 
lesome pest. 
A small dark-colored plant-louse ( Idiopterus nephrelepidis 
Davis)—doubtless of tropical origin—with beautifully marked 
wings, was found on sword fern in several Chicago greenhouses. 
In no case was it a serious pest, but it may become one, and 
should be watched and kept in check by the florist. 
First Knowledge of the Presence of Aerial Plant-lice, and 
their Injury to Plants. —All of the plant-lice above mentioned 
are more or less gregarious, living in colonies on the terminal 
shoots or on the leaves of the plants. Owing, however, to their 
small size and, in many cases, to their greenish color, as also, 
when few in number, to their concealment beneath the folds of 
the immature buds, they are seldom noticed by the average ob¬ 
server until the plants have become considerably infested. 
They obtain their food by puncturing the leaf or stem with 
the beak, or proboscis, through which the sap is sucked. Their 
continual drain upon the sap supply weakens the plant, and when 
numerous the aphids do further damage by stunting and disfigur¬ 
ing the leaves or shoots, as the case may be. 
Life History. —The aphid colonies usually consist of wingless 
and winged females in all stages of development, from the tiny 
young, just born, to full-grown individuals. These adults are 
viviparous and parthenogenetic, that is, they give birth to living 
young without fertilization by the male. In greenhouses which 
are heated in winter, they continue this method of reproduction 
the year round, notwithstanding the fact that outdoors, under 
natural conditions, most of the species are known to develop an 
oviparous generation, females of which lay eggs. 
It requires but a short time—one to two weeks—for the newly 
born aphid to mature, and, in turn, it gives birth to more young. 
Not only do aphids develop rapidly, but they are wonderfully 
prolific, a single individual giving birth to as many as seventy- 
five to a hundred young, at the rate of five to ten a day. Con¬ 
sidering their rapid and enormous multiplication the sudden ap¬ 
pearance of plant-lice in destructive numbers is not surprising. 
Natural Bunnies. —Probably no other group of 'insects is so 
beneficially checked by predaceous and parasitic enemies as are 
*This is apparently the same species as that recently described by Mr. 
C. F. Jackson as Aphis aquaticus, but which I consider to be the European 
Rhopalosiphum nymphdce. 
