OF CORNWALL. 249 
In Cornwall, likely, we have more of thofe infects which require Their 
moderate warmth, fooner and longer in the year, than in other parts 
of England where their colds and heats are more intenfe. I fhall 
not dwell much upon particulars, but in general obferve, that as 
little as thefe creatures are, many undifcoverable to the naked eye, 
fome fcarce to be feen by the beft conftru&ed glaffes, they have 
their ufe, and their necelfary ftation in the animal fcale ; the fmall- 
eft are food to larger, the larger to others of a greater fize, and 
thefe to the greateft ; thefe again to birds and reptiles afford nou- 
rifhment, and fome of them provide food, and phyfick for man ; 
nay the very fmalleft infects fucked in imperceptibly with the air 
we breathe, by their better concocted animal juices, may ferve to 
qualify and corrcdt the acrimony of air, and thereby contribute to 
the fpirit and rectifying of the blood ; add to this, that the fmalleft 
infect as juftly raifes our admiration, and as direCtly leads us to a 
firft intelligent caufe, as the ftructure of a planet or the fabrick of 
the univerfe. By their inconceivable numbers, thefe fmall creatures 
are the great inftruments of divine juftice, and are either the vehicles 
of peftilence, or by their voracioufnefs bring fcarcity, famine, and 
deftru&ion upon a guilty land. 
Ufeful as thefe diminutive creatures are, they muft have their al- Food, 
lotted food ; this food is ufually the leaf of flower, herb, or plant ; 
hither in fwarms they tend, fix, and eat, and neftle their eggs ; 
and when their multitudes are increafed by wind or weather, con- 
fume the bud, the bloffom, or fruit they light upon. Blights 
therefore in the nurfery, fruit, and flower-garden, may with great 
juftice be oftentimes afcribed to fwarms of voracious or poifonous 
infedfcs, but I apprehend not always ; the air itfelf being oftentimes 
charged with corrofive fteams and noxious humours, is of a very 
cauftick nature, and frequently fcorches and fhrivels the fap-veflels, 
and brings on decay. However, there are few plants which do not 
at one time or other fufter in fome degree from infeCts ; nay, ex- 
oticks though they come from another climate, and one would 
think fhould have been the appropriated food of exotick infeCts, do 
not efcape thofe of this climate. Auguft 20, 1750, finding 
the leaves of an orange-tree fpotted as if mildewed, on viewing it 
more attentively I perceived on each fpot an orbicular fubftance thin 
as the leaf, of one tenth of an inch in diameter ; and upon examin- 
mcr it in a microlcope, it appeared to be cruftaceous, in fhape, co- 
lour, and tranfparent fpots on the back, relembling a tortoile , the 
belly-part foon confirmed it to be an animal ; the edges of the fhell 
were thick fet with briftles, by which I imagine thefe animals fix them- 
felves to the leaf on which they are difpofed to feed as well as fence 
themfelves from their enemies : befides thefe marginal appendices, they 
S f f have 
