THE DIPTERA 321 



and fall varieties being in general the greatest sufferers though winter varieties, 

 as the Northern Spy and others, often do not escape. 



The adult flies feed freely and also seem to require water during their life, 

 specimens supplied with food but no water dying within a few days. They do 

 not appear to fly freely for long distances at least, and orchards in which they are 

 abundant and others where they are rather few in number may occur not very 

 far from each other. 



Control. — Infested fruit falls to the ground early, and the maggots in it rarely 

 leave it for the ground to pupate until about a week later. Gathering and 

 destroying this fallen fruit promptly should, therefore, be of much assis- 

 tance in controlling the insect but the amount of labor involved in carrying 

 out this plan makes it impracticable in many cases. Cultivation of the ground 

 under the trees has proved ineffective and allowing poultry and hogs to run in the 

 orchards has not resulted in much improvement. 



It has been found that where orchards are carefully sprayed just about the 

 time the flies appear, using slightly less arsenate of lead than the standard formula 

 and repeating this treatment 2 weeks later, excellent results are obtained. The 

 addition of molasses has sometimes been advised, but comparative tests thus far 

 made indicate little advantage from this considering the extra expense and trouble. 

 To know just when to apply the first spray is a difficulty with this treatment, 

 however, and it has been suggested that owners of infested orchards can place 

 infested apples in a box containing several inches of earth and leave it out during 

 the winter. In the spring, cheese-cloth can be placed over the top and the spray 

 should be applied as soon as the first flies are seen on the under side of the cloth. 



Family Muscidae (The Muscid Flies). — This large family contains 

 many species which are important to man though none appear to be crop 

 feeders. The adults range from small to medium size and arc very 

 abundant in most cases. 



The House-fly {Musca domestica L.). — This insect, always a house- 

 hold pest, has during the last 25 years assumed a greater importance 

 to most people because of the discovery that it is a carrier of a number of 

 serious human disease-producing agents, among these being the germs 

 of typhoid fever, cholera, dysentery, etc. 



The adult flies (Fig. 340) hardly need any description. They are 

 rather small, with reddish-brown eyes, transparent wings and blackish 

 bodies. Their mouth parts are for sucking and a "biting" fly found in a 

 house at any time is of some other species. 



Winter is at least usually spent as the pupa or perhaps in some cases 

 as the larva. As the weather becomes warm in the spring, the flies 

 emerge, and, in temperate regions, begin breeding early in June, though 

 it is probable that in warmer climates this may continue throughout the 

 year. Most of the flies breed in manure piles, particularly those exposed 

 to light, but almost any decaying animal or vegetable matter may be 

 selected for the purpose. The eggs (Fig. 341) are laid in clusters, about 

 125 at a time and about 500 to 600 in all. They hatch in from 8 to 12 



