£ 
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NATURE’S MEANS OF LIMITING THE NUMBERS OF INSECTS. 279 
rarna preys upon the Bostrichus of the larch; Colydium Dae 
Arpi piniper da and B. minor, Læmophlæus hyperbor 
Hyperborus ficus, Hypophleus pini on Bostrichus ei abv ‘i 
finally Hypophleus linearis on Bostrichus bidens. ho will not 
be struck by these antagonisms? Who will not admire this infal- 
libility of instinct which causes these insects to discover the t 
attacked, and perceive, among ‘the species which ‘the tree conceals, 
the victim which has been assigned to them?’ 
“ Other beetles exhibit the same sagacity. The larve of several 
Elaterids (wire worms) and those of Clerus mutillarius and formi- 
carius make war on those of some longicorn beetles of the oak 
the elm, alder bush and the pine. The Opilus mollis and domesticus 
are the enemies of the borers which mine our floors and ceilings ; ; 
the Cylidrus albofasciatus and the Tilus uni fasciatus prey on Sy- 
noxylon sexdentatum and on Xylopertha sea which seek the dis- 
eased branches of the vine, and those of several trees; the 
Tarsostenus univittatus attacks the Lyctus nelodlanie, injuring 
our timber works ; while the Trogosita Mauritanica destroys the 
grain moth.” , : 
We would also add among other efficient laborers in the cause of 
agriculture the lady birds, lace-winged flies, Syrphus flies and 
numerous wasps. But the true parasites, the ichneumon and 
Tachina flies, those which live within the bodies of vegetable-eat- 
ing insects, these are the aids which beyond all other influences 
keep in check the noxious kinds. It may be said that each sort 
of caterpillar has its peculiar ichneumon parasite, and some are 
own to have several. Here we have an engine of destruction 
which man can in some measure direct. We have seen that birds 
eat friend and foe indiscriminately. | The great practical question 
in applied entomology is how can man breed and disseminate these 
insects, and use them as most potent instruments of warfare against 
- insect depredators. This question has been satisfactorily settled 
for the first time by Dr. W. LeBaron, the State Entomologist of 
Illinois. So important and suggestive are his remarks that I 
quote the whole chapter on ‘‘ The transportation of useful parasitic 
Insects” from his able report for 1873, as it deserves the widest 
dissemination among g thinking agriculturists. 
“ The idea of ipa the useful arpa ots and of t 
porting them, when necessary, from one part of the cott To 
another, has often ataino itself to practical entomologists, and 
was a favorite topic of speculation of my predecessor in office, 
D. Walsh. But the very small size of most of these insects, many 
x 
