28 COCKROACHES. 
I have not entered here on the subject of parasitic attacks, for in 
field culture it is most unlikely any attention would be paid to them, 
but perhaps it should be added that where there are little clusters of 
very small yellow cocoons (very like miniature silkworm cocoons) 
noticeable, these should not on any account be destroyed. They are 
the chrysalis-cases of a small ichneumon fly, the Microgaster glomeratus 
scientifically, of which the fly will sometimes lay even as many as 
sixty eggs in one caterpillar of the ‘‘ Large White,” and thus prevent, 
by the parasite grubs feeding within, the caterpillar coming to maturity. 
COCKROACHES. 
German Cockroach; “Croton Bug” (U.S.A.); “Steam Flies.” 
Phyllodromia Germanica, Linn. 
PuyLLopROMIA GrERMANICA.—1-3, adult insects; 2, with wings expanded; 3, 
female with egg-sac attached; 4, egg-sac ;—all magnified; 5 and 6, young, still 
wingless forms. After figs. by Prof. Riley, and specimens. 
Our long-established house and kitchen pest, the Common Cock- 
roach, the Blatta (Periplaneta) orientalis scientifically, and popularly, 
though very inaccurately, known as a Black Beetle, cannot be classed 
amongst crop pests, neither, strictly speaking, can the much smaller 
kind, the ‘‘German Cockroach,” figured above, although on the Con- 
tinent it is sometimes found in woods. Still, as this kind has not yet 
established itself in this country, and if it did so, from its greater 
rapidity of multiplication, and its more general destructiveness than 
our common Black Beetles, it would be such a serious infliction, that 
