806 
[Assembly 
and horny, with numerous impressed transverse lines, and changes 
to a dull yellow or a black color, and those species which have 
two horns forward of the tip still retain them. Within this shell 
the insect puts on its pupa form, from which the fly subsequently 
hatches. 
The aphis likewise has foes within as well as without. In ad¬ 
dition to the several insects of which we have now treated, all of 
which attack it externally, it has internal enemies also, a group 
of insects which dwell in the interior of its body during their 
larva state, and eventually kill it. These are nearly as efficient 
in keeping its numbers reduced as any of those which we have 
been considering. We will speak more particularly of them in 
connection with the aphis which infests the cherry. 
A succession of the several species of these different kinds of 
destroyers are making their appearance the whole season through, 
and as many of these species are among our most common insects, 
it will at once be perceived that they render us most important 
services in destroying these pests of vegetation, and preventing 
them from becoming excessively multiplied notwithstanding their 
unparalleled fecundity. But without actually observing them at 
their accustomed work no one can fully appreciate their value to 
us, and the amount of herbage which they save from destruction. 
Wherever plant-lice become numerous there these several kinds 
of enemies speedily congregate and rapidly multiply, devouring 
incredible numbers of these vermin, and often in a surprisingly 
short space of time completely exterminating them. 
AFFECTING THE FRUIT. 
In a round cavity ate near the tip end of the young fruit; a minute, very slender 
blackish-purple insect, with narrow silvery-white wings upon its back 
resembling along Y-shaped mark. 
The Am.® Thkips. Phlaothrips Mali. 
Although a profusion of flowers in the spring is often hailed as 
a harbinger of a copious yield of fruit, this expectation is very 
frequently disappointed. Whilst they are yet young, quantities of 
