(2) _Diagnosis._ Pigeon flies can easily be observed crawling among the bird’s feathers. Their movement as well as biting greatly annoys the birds. However, the greatest damage they do is transmitting pigeon malaria. (3) _Treatment._ A very effective and easily applied method of treatment is to dust the birds lightly with pyrethrum powder. Sweep nest boxes and loft carefully to collect pupae so that they can be destroyed. Pigeon flies will not travel far from the birds; therefore, keep stragglers out of loft and carefully inspect newly-introduced birds to avoid admitting flies. _d._ MOSQUITOES. Mosquitoes are a very common but usually underestimated pest. Besides molesting the birds by biting and sucking blood, they may transmit pox. These troublesome insects breed in standing water, such as swampy areas, old tin cans, and rain barrels. Control consists of draining or oiling breeding places and using screens on loft openings. _e._ Other parasites attacking pigeons are fleas, chiggers, ticks, bed bugs, depluming mites, feather mites, air sac mites, subcutaneous mites, sand flies, and beetle larvae. Fortunately, these are rare. 54. Internal Parasites These are the worms that live inside pigeons. Round worms are by far the most numerous. Tape worms are occasionally found in pigeons, but seldom present a serious problem. _a._ Ascarids, or common large round worms are the largest and most prevalent of the round worms. Adult worms are from 1 to 2 inches long. (1) _Habits._ Knowledge of the life cycle of a round worm is of great importance for successful control of this troublesome parasite. This worm has a “direct” life cycle (fig. 47) (completing it in one species). (_a_) Mature worms live in the upper part of the small intestines and feed by absorbing food from the intestinal contents through their own body walls. (_b_) Eggs (ova) are deposited by female worms in the intestinal contents of the pigeon, and later pass out in the pigeon droppings. It has been estimated that female worms lay as many as 12,000 eggs a day. Feces from parasitized birds often contain countless numbers of ova. (_c_) Freshly deposited worm eggs are much like freshly laid pigeon eggs, in that they must be incubated before they are ready to hatch. They need to remain in warm, moist litter or soil for 10 to 16 days before the worm larvae can develop. Severe freezing, excessively hot soil, and direct sunlight will destroy the eggs. (_d_) When birds eat the incubated eggs, the worms hatch out in their intestines. (_e_) The tiny larvae then “sew” themselves into the lining of the intestines and begin to grow. (_f_) After a few days, the larvae crawl back into the intestinal canal where they mature in 30 to 40 days. (2) _Diagnosis._ Ascarids injure birds in several ways.