8 
the healthy wintering scales of the Wytilaspis will be found a varying 
number of sound eggs, but seldom less than 50, while nearly 100 may 
be found in a few. Examinations which Mr. Pergande made for me in 
the early spring of 1895 showed that while some of the specimens of 
Aphelinus liad issued from the scales late the previous fall (evidently 
considerably after the egg laying of the females had been completed), 
others were present in the full-grown larval condition, ready to trans- 
form to pup. The latter were in the great majority. In no ease, 
however, had all of the scale-insect eggs been devoured, even with 
those scales from which the parasite had emerged the previous autumn. 
Under these latter scales from 5 to 11 sound eggs were found, while 
under the scales containing full-grown parasitic larvie from 2 to 18 sound 
eggs were found. It seems, therefore, that the work of the last gener- 
ation of Aphelinus is no more effective than that of a ladybird beetle, 
probably not so much so, These beetles tear open the scales and eat 
the eggs, but frequently do not eat them all. In the latter case, how- 
ever, the exposure of the eggs may result in their death, whereas the 
eggs which are left by the Aphelinus will undoubtedly hatch. It is 
unfortunate that the Aphelinus larva is not capable of eating every- 
thing in sight in the shape of Mytilaspis eggs, but we must take the 
facts as we find them, and it is plain that the good work of these para- 
sites has been overestimated. 
When these insects are properly mounted they are not especially diffi- 
cult to study. The yellow forms have a delicate exoskeleton, and when 
mounted dry shrivel to some extent. The face falls in and the thorax 
becomes distorted. If thrown into alcohol they become discolored. If 
mounted in balsam they also become more or less discolored. All the 
yellow forms should be mounted in glycerin in a thin cell of Bruns- 
wick black. They should be mounted under a lens, and some care 
taken to spread the wings, legs, and antenne. Several specimens may 
be mounted to advantage under a single cover glass. In all cases, how- 
ever, it is important that a colorational description be drawn up from 
fresh material, since even with glycerin mounts the colors change to 
some extent and become more sordid. With the black species, as of 
Coccophagus, the shriveling is not so liable to occur, and the larger 
species particularly can be studied to advantage from dry mounts on 
tags. Even so, however, where more than one specimen of a given 
species is collected or reared, it is very advantageous to mount a por- 
tion of the series in glycerin, as above described. Details of struc- 
ture, aside from sculpture, can be more readily studied from slide 
mounts. 
Twigs and leaves infested with scale insects from which it is expected 
that these little parasites will issue are preferably placed in small, wide- 
mouthed jars, the mouth of each jar being wide enough to admit the 
hand. The mouth of the jar is then covered with thin muslin held 
