ORDER DIPTERA.

The name of this order was first used by Aristotle, and is a compound of two Greek words signifying twice or two, and wings; that is, "Two-winged insects," although there are a few species belonging to it that are entirely wingless. The insects included in it are commonly called Crane-flies, Mosquitos, Gnats, Bot-flies, Horse-flies, Ox-flies, Blow-flies, House-flies, &c., &c. They are characterized by having a single pair of wings, which are membranous and usually extended, and affixed to the middle of the sides of the thorax. Near the insertion of the wings are a pair of small appendages called halterers. The mouth is provided with a haustellum composed of from two to six scaly lancet-like pieces, inclosed in a groove or canal upon the upper surface of a fleshy snout or proboscis; or covered by one or more inarticulated plates, forming a sort of sheath. The antennæ exhibit various degrees of development, from very short to very long. The ocelli, when present, are three in number, and the eyes are large, lateral, and composite-those of the males in many instances being much larger than those of the females. The abdomen is usually attached to the thorax by only a portion of its basal dimeter, and is generally more pointed in the females than the males. The tarsi are five-jointed and terminated by a small pair of hooks, and often by a sort of cussionlike process, which enables the insect to walk on a very smooth surface, or with the ba downward. The larvæ are usually called "maggots," and there is less diversity in their transformations than there is in some other orders, or than the diversities in the mature insects would seem to imply. Lancaster county, occupying a geographical position intermediately between North and South, has many species within her borders that are common to either of those portions of our territory, but the local Diptera of the county is only very partially developed in history and classification.

CULEX Linn.

CULICIDE.

damnosus Say.

pipiens Linn.

cingulatus Fab.

ciliatus Fab. pungens Weid.

colon Har.

ANOPHELES Mei.

granulatus Har.

quadrimaculatus Say.

TIPULIDE.

TIPULA Linn.

alternata Say.

trivittata Say.

flavicans Fab. ferruginea Fab. tricolor Fab. nubilis Har.

CECIDOMYIA Fab.

grossularia Fch.

tritici Krb.

robinia Hld.

inimica Fch.

cerealis Fch.

graminis Fch.
destructor Say.
salicis Fch.

culmicola Mor.
CTENOPHORA Mei.
abdominalis Say.

MOLOBRUS Fch?
mali Fch.

vulgaris Fch.
inconstans Fch.

fuliginosus Fch.
PTYCHOPTERA Mei.

clavipes Linn. LIMNOBIA Mei.

rostrata Say.
scutellata Say.
RYPHUS Lat.

alternatus Say.
discoidus Say.

CHIRONOMUS Mei.

albitarsis Har.

claracollis Har.

lateralis Har.

biplagiatus Har.

SIMULIUM Lai.

obscurum Har.

calceatum Har.

confluens Say.

falconis Har.

MELOPHAGUS?
ovinus Linn.

My scientific knowledge of the Diptera of Lancaster county is very limited, and therefore the foregoing catalogue of these insects is nothing more than an imperfect compilation from the works of Say, Harris and Fitch-with Harris' classification—as an approximation to what may be presumed to be the dipterous fauna of the county, from its geographical position, and its relation to other portions of the northern and middle States of the Union. S. S. R.

ORDER APHANIPTERA.

This is the order APTERA of Macley, and includes the wingless insects; an example of which is the common "Flea”—Pulex irritans. Not all insects however, that are destitute of wings, are members of this order; for there are various species, the females of which are wingless, and in some instances both sexes, in other orders. As instances of this kind, it may be remarked, that several species of predaceous Coleoptera are wings less, although they have wing-covers. There are also wingless species both male and female among the Orthoptera; and females among the Hemiptera; and among the Hymenoptera, and Lepidoptera, as well as the Diptera. This subject constitutes one of those anomalies in natural history, which can only be solved by the patient and persevering progress of the entomological student. The order Aphaniptera might perhaps be properly restricted to a single small family. PULECIDE, which includes the various species of fleas, that infest men and animals. The PODURIDE, which by some entomologists are regarded as degraded species of Neuroptera, may, for the present with some propriety, beplaced in this order. These insects undergo the usual transformations, from the egg to the imago, that all other insects do, but they lack the distinctive divisions of head, thorax and abdomen, that characterizes the other orders, being merely a series of segmental rings, from the head to the caudal termination of the abdomen. In their larva state they are long, distorted, wormlike grubs, which however spin themselves into a sort of silken coccoon, and assume the pupa form, in which the legs, antennæ, and sucking apparatus are visible. Emerging from this state, they assume the mature form, in which the Pulecido have the hind feet developed into leaping appendages, and the external integument tough and shiny, each segment being fringed with a few stiff bristles. In this form they attack men and animals, living upon the blood they extract from them by means of their powerful piercers.

The Podurida, as before stated, are regarded by many naturalists as merely degraded forms of Neuroptera, allying them with the genera Ephemera and Perla, and therefore perhaps they cannot properly be classed with the Order APTERA, scientifically restricted.