Nov. 1, 1893.] SupplemPAxt to tho " Tropical AgricuUurist.''' 
355 
previous July and August." The value of a dead 
mulch is unquestioned by any. In some wiiy 
both live and dead mulches favor nitrification 
in the soil, and the earth is made richer apart 
from the decay of the covering. Rven a cover 
of boards, or stones is known to bring about 
enrichment of the soil. Concerning the value of 
a crop for ploughing under, the common verdict 
stands in high approval. Any crop is considered 
valuable for the purpose. That a crop of ordin- 
airy weeds is as valuable as one of clover, 1 do 
not claim. Yet it is not improbable that some 
among the miscellaneous growth may be nearly, or 
quite, as good a collector of nitrogen as the clover. 
To place an estimate on the aggregate benefit 
of weeds would be a difficult task. That it is 
sufficient to be worthy of consideration, is a fact 
that can hardly be questioned. On the great 
Western American farms they furnish about all 
the fertility that is ever received. It is not 
improbable that they do much more in keeping 
up the continued richness of soil than is ever 
credited to them. The fall crop of weeds costs 
nothing. If a system of agriculture shall make 
profitable use of them, it saves the hard work of 
keeping them down. There is also a great saving 
of worry over conditions that are often unavoid- 
able. 
ZOOLOGICAL NOTES FOR AGRICULTUA.vL 
STUDENTS. 
In the last instalment of these notes reference 
was made to the various orders of Insecta, and 
especially those which were most harmful to 
agriculture. We do not purpose taking up in- 
dividual insects and i-eferring to their physio- 
logical characteristics add habits of life in detail, 
for we .shall then be encroaching u^Don the domains 
of the science of entomology. We would, how- 
ever (to show the importance of an acquaintance 
with this sub-kingdom of zoology), jioint out that 
nil insects may bo roughly cassified as biting insects 
{Mandibulata) and sucking insects {Ilaux/ellata): 
to the former class belong the Coleoptera, Ilyme- 
noptera, Orthoptera and Neuroptera ; to the 
latter, Lepidoptera, Homoptera, Heteroptera and 
Diptera. The biting insects (the beetles for in- 
stance) are furnished with two pairs of jaws, the 
mandibles for biting, the maxillse for chewing. 
In the sucking insect (such as the butterfly) 
the maxilhe are transformed into two long slender 
tubes so as to form a canal through which 
liquids can be sucked; this canal, which can be 
(•oiled up when not in use, is called the proboscis. 
From what has been said, students will to some 
extent be able to classify insects as biting or 
BU 'king insects, as well as, in some measure, to 
phK;e tliem in tlie different orders in which they 
have been grouped principally according to the 
structure of their wings. But it is often not so 
easy to state the natural order to which a 
mature insect belongs. Beetles, moths and 
dipterous insects are sufficiently distinct ; but 
as many insects (all those that pass through 
a complete metamorphosis) are specially destruc- 
tive to vegetation in the larval stage, it is of 
practical importance, — especially with a view to 
adopt remedies — Lo be able to determine of 
what order a larva is a member. 
Dr. Fream gives the following as a guide to 
tliis process of identificati n : — "A legless 
flesliy grub, with a soft, fleshy, retractile head 
(a maggot ') is umrdli/ ont of the diptera. 
An active six-legged . grub, with a horny head 
and strong jaws, is usually that of a beetle 
(coleoptera). The so-ealled caterpillars, long, 
soft (sometimes hairy), with prominent head ami 
jaws, and, furnished , with sixteen legs, belong 
to the lepidoptera. When several of the inter" 
mediate legs are absent, a "looper" caterpillar 
results. Active leaf-eating larv;e, with from 18 
to 22 feet, usually belong to the hymeiioptera, 
and are termed " false caterpillars." It 
will be seen from the foregoihg notes that a 
knowledge of the zoology of insects is most im- 
portant, iu that it helps us, in a great measure, 
to find the means of dealing with them when 
they appear as agricultural pests. Tlie biting 
insects which destroy vegetation by gnawing, can 
be reached by some jxjison (e.ff., arsenical com- 
pound) thrown on the lekf itSelf, so that when 
they consume the leaf, they also take in the 
poison and are killed. - In the case of the suckino- 
insects, something (e.ff., kerosine) must be 
forcibly thrown on them, which in itself is fatal 
by contact. It should also be borne in mind that 
insects breathe by me ins of air-tubes t^tracheje) 
which open at the surface of the body, so that 
by clogging up these pores with powders or other 
materials, an insect may be suffocated, and many 
methods of destroying insect pests are based on 
this fact also. 
N.B. — In the August number, in enumerating 
the characteristics of the individuals belonging to 
Insecta, they were said to " breathe by means 
of trachwa," (wind-pipe). This last word should 
have been trachere (air-tubes). 
^ 
THE DAIRY. 
Never allow your cows to be hurried to and 
from the pasture, and never allow a dog to worry 
them. In fact a dog is a useless thing around 
cows. He invariably barks or in other ways 
annoys them. Cows should be kept as quiet as 
possible, that the milk may be normally secreted. 
It is a disappointing time when one sees the 
calf that has been growing thriftily while fed 
by its mother, begin to look rough in the hair 
and thin in flesh, as it comes to the changed con- 
dition of feed when once it has been weaned 
It is just here that much of the trouble comes iu 
attempting to raise calves. It is the suddenly 
changed condition of food that damages the 
small animal's digestive organs, and for a while 
appears to stop its growth entirely. The remedy 
is the making of the ciiange from the mothers 
milk to the new food as little of a change as pos- 
sible at first, and to make this change very gr.i- 
dually. The great point is to make the change 
so gradually as not co disturb the digestive 
functions, and no small part of the care required 
to do this is having the prepared food always 
of the warmth of new milk. After it has yrrown 
strong an<l lusty on its new diet, the call may 
have some grass or hay, but .not too much, us 
by ov(jrta.\.iag both the capacity and digestive 
