390 
larger seaports during the summer months, 
almost none have succeeded in getting a 
foothold in the vicinity. Mr. Otto Lugger, 
when living in Baltimore, Md., made a col- 
lection of many species of foreign insects 
found upon the wharves, yet he has record- 
ed the establishment of but a single species, 
viz, Aphodius erraticus, an European dung- 
beetle, which managed to get to Druid Hill 
Park, where it bred in the dung of the tame 
deer, afterwards spreading into the sur- 
rounding country and breeding in the dung 
of sheep and other domestic animals. 
Practically, therefore, after many years 
of the most active commerce, the insect 
faunas of the immediate vicinity of the 
larger seaports, like New York, Boston, 
Philadelphia and Baltimore, have not been 
greatly changed by the introduction of 
foreign elements. 
All of the household insects and true city 
insects are, of course, exceptions, to this con- 
clusion and the strong flying, vigorous, and 
simple living dipterous insects—the very 
ones most likely to enter a loading vessel 
and to escape on the discharge of its cargo— 
will many of them find proper places for 
breeding. It is likely that a much larger 
proportion of the many species of Diptera 
common to Hurope and North America 
have been brought over in this accidental 
manner than is the case with the Coleoptera. 
But often these purely accidental species 
are carried inland in packing eases, into the 
eracks of which they may have crawled, or 
even in the trunks of passengers, and they 
may then be liberated in more favorable 
localities. For example, Mrs. H. G. Hub- 
bard, after spending the summer on Prince 
Edward’s Island, returned in the autumn to 
Detroit, Mich., and in unpacking her trunks 
her husband found two specimens of 
Phytonomus punctatus, a species not pre- 
viously known to occur in Michigan, al- 
though found there in injurious numbers a 
year or so later. It is altogether likely 
SCIENCE. 
[N.S. Vou. VI. No. 141. 
that the imported elm leaf-beetle ( Galerucella 
luteola), an insect which enters houses for 
hibernating purposes, was first brought to 
America in this manner. 
It is, however, the accidental commercial 
importations which theoretically stand the 
best chance of establishing themselves, since, 
in the first place, they are generally im- 
ported in or upon their natural food. In 
the second place, they generally occur in 
considerable numbers, instead of as isolated 
individuals, as with the more purely acci- 
dental importations; and, in the third 
place, they are usually carried as originally 
packed, far from the port of entry. 
With insects brought over on plants or 
nursery stock the conditions could not well 
be much more favorable. Their supply of 
food is looked after with care, the host 
plant is soon put in the ground in the 
best of surroundings, and the greatest care 
is taken of the choice importation. Upon 
or in importations of this kind are carried 
Coccidee in all stages of growth, and often, 
fortunately, their enclosed parasites, the 
eggs of Aphididee, the larvee of wood-boring 
Coleoptera, the eggs of many other insects, 
the cocoons of small Lepidoptera, and prob- 
ably even in rare cases the larvie of Lepi- 
doptera, since it now seems likely that 
Euproctis chrysorrhea was imported into 
Massachusetts on nursery stock in its larval 
hibernacula. The Coccidee, however, are 
most abundantly carried in this way. 
Under natural conditions these insects have 
usually a rather restricted distribution, but 
by means of this commercial distribution 
many of them have become of almost world- 
wide range, and the end will certainly not 
be reached until every country possesses 
every species of scale insect which can 
possibly live in its climate. A few instances 
drawn from a recent paper by Mr. Cockerell 
will illustrate this fact : 
Diaspis amygdali, or lanatus, was described 
from Australia in 1889. To-day we know it 
