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THE GAD-FLY. 
One of the wonders of natural science is the Army-worm (Heerwurm). At first sight, it 
appears to be a single being, but by closer observation it will be seen to consist of a vast mul- 
titude of larvae, or caterpillars. There is a European and an American Army-worm, distin- 
guished from each other by the nature of the tiny creatures which collect in a body for pro- 
cession or migration ; the one being a collection of the larvae of the small light yellowish gnat 
(Sciara militaris), belonging to the family MycetopJdlidce of this class, while the other consists 
of the caterpillars of one of the moths of the family Noctuidce. 
When in such a large collection, the larvae of the Sciara militaris move forward in a 
snake-like manner. They look pallid, and are kept closely together by their mucous surfaces, 
so that they really appear as one body. So strongly do they stick together, that the tail-piece 
of the worm may be lifted with help of a stick for a moment without becoming refracted. 
r lhe faculty of moving on consists in the uniform motions of all the larvae. Every one shoves 
forward with the back of the body, and then stretches out the fore-part as if feeling. The 
whole appears like a little stream slowly gliding along. 
Sometimes this larvae-procession has to overcome obstacles in its way which often cause a 
dissection. Small hindrances the Army- worm surmounts, but larger ones cause a temporary 
disunion. Sometimes one part of the mass of bodies disappears under leaves, but generally a 
reunion takes place. A break by force, caused, for instance, by the hoofs of a horse, or by the 
wheels of a wagon, soon becomes joined, just as is the case with the so-called procession-cater- 
pillar of the moth Cnethocampa processionea, belonging to the family Bombycidce , of the 
class Lepidoptera. 
For centuries, the mysterious movements of the Army-worm have given rise to all kinds 
of superstitious beliefs among the people of Europe, where from time to time it was seen in 
Silesia, Thuringia, Hanover, Denmark, Norway, and Sweden. They predicted luck or mis- 
fortune from its appearance, some prophesying war, others the result of the harvest. The 
inhabitants of the Silesian mountains predicted luck, whenever the Army- worm took its way 
down the valley, but unfruitfulness whenever it crawled up. The people in the Thuringian 
woods predicted peace when it took the former direction, and war when it took the latter. 
Some even believed their own destiny to be connected with the worm. They threw clothes 
and ribbons in its way, and felt happy, especially hopeful women, when it crawled over the 
things ; but they regarded one as a dead man whose things it avoided. 
These funny beliefs are now all overthrown by the studies and close observations which 
Mr. Beling, an inspector of the German forests, has made of the Army- worm. He detected its 
exact nature and origin, and he has delivered many treatises on the subject since the year 
1868 . His observations fully convinced him that the only cause for the appearance of the 
Army-worm is the longing for food of larvae of the Sciara militaris. The Army- worm gener- 
ally measures fifteen feet in length, and three to four inches in width. 
Though really not belonging to the Diptera , but, like the Cnethocampa processionea , to 
the Lepidoptera , we may undertake here, for sake of conformity, to treat the American 
Army-worm. The caterpillars forming it are termed Leucania extranea. They collect, like 
the European Army- worm, in vast numbers, and devastate whole meadows in a short time. 
When they can no longer find grass, they emigrate to other fields, and 
attack even rye and wheat. Large clusters of these caterpillars have 
been observed in the Western States and on Long Island. In 1861 , such 
a gathering of caterpillars proceeded fully sixty yards in two hours. 
The Texas and Mexican collections of the same or of a similar spe- 
cies of caterpillars are known by the name of Wire-worm. 
The accompanying illustration represents the common Breeze- 
fly, a well-known example of the Tabanidae. It is also known by the 
popular names of Gad-fly and Cleg. As in the gnats, the females are 
the only bloodsuckers, but they exert their sanguinary ability with 
terrible force. While staying in forests and suffering greatly from the bites of the Gad-flies, 
I used to keep a little naphtha in a bottle, and rub it occasionally over my face and hands, for 
GAD-FLY (Female). — Taba- 
nus bovinus. With the head. 
(Natural size.) 
