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THE SHEEP BOT-FLY ( Oestrus ovis L.) 
As this is a true insect belonging to one of the most numerous 
orders of the class, I will, before describing it, give a brief outline of 
the larger divisions of the order. The arrangement I will adopt is 
that given by Westwood in his “ Introduction to the Modern Classifi¬ 
cation of Insects ,” not the latest, it is true, but sufficiently accurate 
for the present purpose. 
As stated in my first report, the insect class is usually divided into 
about seven orders, as follows: 
Order 3. 
Order 4. 
Order 5. 
Order 6. 
Order 7. 
Order 1 . Coleoptera , containing the various kinds of beetles. 
Order 2. Orthoptera , containing the cockroaches, walking-sticks, 
grasshoppers^ crickets, etc. 
Neuroptera , containing the dragon-flies, lace-winged flies, 
etc. 
Hymenoptera , containing the wasps, bees, hornets, ich¬ 
neumon-flies, etc. 
Lepidoptera , containing the various butterflies and moths. 
Hemiptera , containing the true bugs, such as the bed-bug, 
squash-bug, chinch-bug x cicadas, plant-lice, bark-lice, etc. 
Diptera , containing the two-winged flies, such as mosqui¬ 
toes, house-flies, horse-flies, bot or breeze-flies, sheep- 
ticks, etc. 
As will be seen from this, the bot-fly of the sheep belongs to the 
last order Diptera , or two-winged flies, but some, as the sheep-tick 
and other species, as is the case in some instances in the other orders, 
are without wings during their entire lives. 
This order, as before intimated, contains an immense num¬ 
ber of species and has been divided into numerous families 
which cannot be noticed here. On this account entomolo¬ 
gists have divided the order into sections according to the 
character they conceived to be of most importance, the di¬ 
vision by Westwood is as follows: 
Sect. I. Head always distinct from the thorax; claws of the tarsi 
not dentated or toothed; larva annulose, not undergoing its 
transformation to the perfect state within the body of the 
parent. 
Divis. 1. Antennas composed of more than six joints; palpi four or 
five-jointed; pupa incomplete. 
Musquitoes or Gnats, Crane-flies, Wheat-midges, Hessian- 
fly, etc. 
Divis. 2. Antennae short, not having apparently more than three 
distinct joints; palpi one or two-jointed. 
A. Antennae apparently composed of only three joints, the last 
however being articulated; proboscis exserted, seldom en¬ 
closing more than two lancets; the pupa coarctate, the skin 
of the larva, however, nearly retaining its previous form. 
Contains mostly bright-colored flies found on flowers. 
B. Antennae with only three joints, usually with a bristle near 
the end, ( Tabanus or horse-flies form an exception); pro¬ 
boscis exserted, usually with four, sometimes six lancets; 
larva with a scaly head; pupa incomplete. 
