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48 
peach trees, but they appear to be quite partial to pears. I have 
killed perhaps a thousand of them in my pear orchard this spring. 
My pear orchard consists of two thousand trees, set two years ago.” 
In a subsequent letter, dated May 10th, Mr. Ayres makes the 
following additional statements: u The caterpillars of the kind 
first sent have all disappeared. I think they must go through 
their transformations under ground, or else somewhere outside of 
the orchard ; nor do I think that the eggs are laid upon the pear 
twigs, for I should certainly have found some of them.” He goes 
on to say that he thinks they must pass the winter in the caterpil¬ 
lar state, from the fact that he had seen no very small caterpillars, 
but that they make their appearance all at once, from one half to 
fully grown, though he had seen a very few not more than one- 
quarter grown. He adds that they appear to be very migratory in 
their habits, and that he had killed a caterpillar nearly every day 
for a week on the same small tree, one taking the place of another. 
Of the seven caterpillars sent, one must have been lost, as I have 
a record of only six- One was put in alcohol and preserved in the 
larva state; two were taken into Chicago to be delineated and en¬ 
graved, and died from not being properly supplied with food. 
The other three were put into a glass covered box and regularly 
fed with pear leaves. The box was partly filled with earth, that 
they might go into it to transform if it were their nature to do so; 
and some chips were laid upon the earth to which they might at¬ 
tach their cocoons. On the 13th and 14th of the month, that is 
about a week after I received them, two of them crept under the 
chips and inclosed themselves in their cocoons, into which little 
bits of loose earth were woven so that nothing but the earthen par¬ 
ticles were visible. The other continued to feed ten days longer, 
till the 24th of May, when it made its cocoon like the others, of 
web and particles of earth, attached to the under side of a chip. 
Two of them, owing probably to the unnatural conditions to which 
they were subjected, failed to come to maturity. One of tjiem for¬ 
tunately completed its transformations, which was all that was 
necessary to determine the species. 
The perfect, or winged form of this insect, is a whitish moth with yellow markings; 
the body three-quarters of an inch long, and the wings expanding two inches. The gen¬ 
eral color of the body and wings is white, with a satiny lustre, and with a scarcely per¬ 
ceptible yellowish tint. The antennae are blackish-brown. Palpi yellow tipt with brown. 
The head, collar, scutellum and first segment of the abdomen are yellow; as are also the 
