32 MISC. PUBLICATION 318, U. 8S. DEPT. OF AGRICULTURE 
Horseflies.—In the horse-and-buggy days many runaways were 
caused by large black flies highting on the horse. The group of flies 
_.__. to which this species belongs are called horseflies. 
They vary considerably in size and can be dis- 
tinguished by the peculiar shape of the head, 
which is nearly all eyes and fits over the front part 
of the body cap fashion. The adults have two 
wings and piercing mouth parts. They feed on a 
number of animals. Horseflies have complete life 
changes and spend the winter as larvae in mud. 
Although these insects are pests, there is no effec- 
tive control except drainage of the marshy areas 
in which many kinds breed. The black horsefly 
pictured here is Z’abanus atratus. This species is 
from 8/4 to 114 inches long. 
FIGURE 79.—Horsefly. 
Robber flies.—Can it be possible that when man desired more speed - 
in the air he looked to the robber flies? Most robber flies are rather 
large. Even though they have but two 
wings they are capable of flying very fast. 
They feed almost entirely on other insects. 
The head of the robber fly somewhat re- 
sembles that of the horsefly, but its neck 
is much longer. The adult has piercing 
mouth parts. These insects usually winter 
as larvae or pupae in the ground, 
where the larvae feed on worms and 
larvae of other insects. Like all other A 
Diptera, the robber fly has complete life Fegan 80 = Ronee. 
changes. The one shown here is Prom- 
achus rufipes, which attains a length of from 1 to 1% inches. 
Mosquitoes.—What person has not heard the buzzing of a mos- 
quito or felt the mouth parts pierce an exposed part of the body? 
This group of Diptera possibly causes as much annoyance to people, 
especially picnickers, as any other insect. It is 
only the female mosquito that can bite, and not 
all kinds of mosquitoes feed on man or animals. 
In addition to causing annoyance from feeding, 
some mosquitoes are responsible for carrying dis- 
eases such as malaria and yellow fever. Malaria 
is a major health problem in this country. All 
mosquitoes have a long, narrow body with com- 
paratively long legs and two wings. The hfe 
changes are complete. The larvae, or “wigglers,” 
are found in stagnant water. Mosquitoes breed 
commonly in rain barrels, cisterns, ponds, and 
other places where water stands for a few days. 
Such accumulations of water should be tightly 
covered, or the surface treated with a light film of kerosene or oil 
every week. If possible, stagnant pools should be drained. Mos- 
quitoes are usually much smaller than crane flies, and can be dis- 
tinguished from crane flies by the tiny hairs on the margins of the 
wings. The one shown here is the yellow-fever mosquito (Aedes 
aegyptz), which is about three-sixteenths of an inch long. 
FIGURE 81.—Mosquito. 
