July 1, 1893.] Supplement to the '* Tropical Agriculturist. 
67 
RED SPIDER. 
The Red-Spider Tetranychus telarius familiar 
to agriculturists, is not a true spider but a spin- 
ning mite. It is distinguishable from the true 
spider in having its body and abdomen united 
into one piece, and not merely joined by an almost 
thread-like connection. "When mature the red- 
spider is oval, furnished with four pairs of legs, 
two pointing backwards and two forwards ; the 
head, body and abdomen form a solid mass, by 
which, as before mentioned, it is distinguishable 
from the true spiders which have the abdomen 
joined to the rest of the body by a fine stalk; 
and also from insects which have the head, body 
(thorax) and alidomen commonly distinct from each 
other, and which in their perfect state have never 
more than 3 i^airs of legs. The head is furnished 
with a beak or sucker by means of which it 
draws the juices from leaves, and beneath the 
abdomen is a conical protuberance from which 
the threads are produced with which it forms its 
webs. The colour is various ; of transparent 
yellowish white, orange red, or brick red, and other 
tints depending, as far as present obiCVction 
shows, on the colour and nature of the food 
within, and partly also upon the age of the indivi- 
dual, as these mites have been noted as of a green 
colour in early life, changing with maturity to 
the rust colour we are best acquainted with. 
Entomologists are not yet agreed whether there 
are different species of the red spider or whether 
the pests that attacks different forms of vegeta- 
tion are all varieties of the one species. Mr. 
Murray, in his Handbook of Economic Entomology, 
thus describes the work of the mite: On leaves 
(especially the under side of them) it finds a fit 
hold, and spins its web, affixing the threads to I 
the prominences and hairs of the leaf ; and under 
this shelter a colony, consisting of both sexes 
in maturity, and young of all ages, feed and 
multiply with rajjidity. The plant soon shows 
the influence of their presence in its sickly yellow 
hue ; the sap is sucked by myriad insect-mouths 
from the vessels of the leaf, and its pores are 
closed by excremental fluids. The red spider 
causes enormous damage to hops in England 
(where it also attack the lime-tree, plum, rose, 
clover, &c.) in dry seasons, and its effect upon the ! 
leaves was until recently attributed to heat and 
drought and was called " fire-blast." These mites 
which are scarcely discernable by the naked eyes 
(except when collected together) spin their 
webs over the stems and branches and 
beneath the leaves of infested trees, giving 
a sort of glaze or silking lustre to the surface, [ 
and on this web they can travel easily. ' 
Many preventatives against, and remedies for, ' 
red spider attack have been suggested, most of 
which are to be found in Miss Ormerod's " Manual 
of Injurious Insects." It is to be noted that the , 
red spider dees not thrive in the presence of 
moisture. Washing (by means of syringes or garden 
engines) with soft soap and water or even with 
pure water is one remedy. Miss Omerod advises 
banking round the tree at a few feet distance and a 
few inches high, and filling the space enclosed 
.with mud made as thin as would be retained by 
the raised edge. A liberal mixture of fish oil and 
soft soap so as to completely plaster round the 
toot of the tree aud stick all the wandering 
mites fast that touched it, could not fail to do 
good at a trifling co.st. Sulphur is said 
to be one of the most active aud efficient agents 
in jjreparations for destroying red spider, and 
sulphur and soft soap combined are among the 
most reliable remedies. One pound of flour of 
sulphur and 2 lbs. of fresh lime (an alkali is 
necessary for dissolving of sulphur in water) boiled 
in 4 gallons of water is a good mixture for wash- 
ing. Miss Ormerod gives the following recipe : 
3 gallons gas water, 1 lb. of flour of sulphur : 
these to be held over the fire while being mixed 
and soft soap added in such quantity as to 
make the mixture adhere. This may be applied 
to the branches with a brush, or after being 
diluted to a state in which it is a safe appli- 
cation, the liquid may be thrown over the leaves 
by means of a garden engine or spraying machine. 
Probably 15 parts of water to one of the mix- 
ture would be about the proportion, but this 
should be decided by trial. 
« . 
ZOOLOGICAL NOTES FOR AGRICULTURAL 
STUDEA'TS. 
Arthropoda (or articulata, from the fact of its 
members possessing jointed appendages articulated 
to the body,) comprises the Crustacea (lobsters, 
crabs, &c.) Arachnida (spiders, scorpions, &cj, 
Myriapoda ''centipedes ), and lastly the imp Drtant 
class Insecta. The Crustacea, the majority of 
which are aquatic, include also, besides crabs 
and lobsters, the shrimps, water fleas, woodlice, 
barnacles and sand-hoppers. The Arachnida com- 
prise, in addition to the scorpions and spiders, 
mites and ticks. Spiders are all carnivorous, 
living upon other animals, and all of them 
possess the power of constructing webs, which 
they employ either in the capture of their prey 
or in the construction of their own habitations. 
The material of which the web is made is the 
secretion of a special gland, and it is moulded 
to its proper shape by being passed through 
certain conical little organs which are placed 
at the extremity of the abdomen, and are termed 
" spinnerets." The spinnerets are either four or 
six in numbers and each has its apex perforated 
by a great number of little holes. The silk is 
at first fluid, and hardens rapidly on being 
exposed to the air. A single filament of silk 
is thus produced by each of the perforations 
in the spinneret, so that what we call a single 
" thread " in a spider's web is reallj' a cable, 
composed of a great number of the most delicate 
fibres agglutinated together. Many species do 
not form regular webs, but they all use the 
silk to form little cases or " cocoons " in which 
the eggs are protected, and which the parent 
sometimes carries about with her. Some claim 
the garden s^jider as a friend to the Agriculturist, 
explaining that it destroys many of the insects 
injurious to plants, and that its web often pro- 
tects plants from the force of wind; but this 
is doubtful. 
The mites and ticks are grouped under the 
order Acarina. The mites (acari) include many 
species injurious to plant life, and specially to 
fruit trees. As instances may be mentioned tlie 
red-spider," which is really a mite, and tlie 
orange rust mite Acarus domesticus is tliQ 
