No. 64] DIPTERA OF CONNECTICrT 7 



Although flies have some g-oocl attributes, they are as a group 

 undoubtedly much more detrimental than useful. JNfany species are 

 disgusting nuisances, as cheese skippers and fruit maggots, which 

 cause food to be rejected. However, if we consider for a moment 

 the injury of some species to useful plants, the diseases of man 

 transmitted by others, the parasites of domesticated animals, and the 

 nuuiber of intolerable venomous biters included among- these insects, 

 we can obtain some conception of their economic importance. 



Species injurious to useful plants are found in many families of 

 Diptera. The crane-fl}^, Nephrototna ferruginea^ sometimes becomes a 

 serious pest of young tobacco stands, eating the parts of the plant 

 under ground. The gall midges of the family Cecidomyidae are 

 frequently serious pests. The Hessian fly, although not of economic 

 importance in Connecticut, has a bad reputation in wdieat-growing 

 regions of the country. The leaf-miner of boxwood also belongs in 

 this group. The fruit flies of the family Trupaneidae include the 

 apple maggot, Rhagoletis pomoneUa^ two other species of the same 

 genus which cause wormy cherries, and the leaf-miner of parsnip, 

 Acidia fratria. The larvae of two species of the agromyzid genus 

 Phytomyza mine the leaves of columbine, and species of the genus 

 Agromyza mine the cambium of birch and maple trees, causing "pith 

 flecks". The larvae of the Psilidae live in roots of plants and in 

 galls, and one species, the carrot rust fly {Psila I'osae), injures car- 

 rots. The family IMuscidae has among its members four notorious 

 species, the cabbage maggot {H ylemy'm brassicae) , the seed-corn mag- 

 got {S. cillcrm^a), the onion maggot {H. aniigua) ^ and the spinach 

 leaf-miner {Pegomyia hyoseymni). Even the Syrphidae, beneficial 

 in many instances, include such pests as the bulb-flies {Merodon). 



There are a great number of blood-sucking flies the adult females 

 of which bite man and domesticated animals. Some of these are 

 simply venomous biters, and they may be serious pests, but many 

 also transmit diseases when they bite. The very small "no-see-ums", 

 midges of the family Ceratopogonidae, often make life miserable 

 near bodies of water in the summer. Both salt marsh and fresh- 

 water mosquitoes are frequently iniquitous, and the species of Anoph- 

 eles are the sole carriers of malaria. The horse-flies (Tabanidae) 

 are notorious pests of live-stock, and members of the genus Chrysops 

 often attack man. They may be implicated in the transmission of 

 some diseases of horses and cattle in parts of the United States. 

 Black-flies (Simuliidae) are also serious pests of man and domesticat- 

 ed animals by virtue of their poisonous biting. Among the ^luscidae 

 are two well-known pests of live-stock, the stable-fly • {Stomoseys 

 calcitiuns) and the horn-fly {Ilaenmtobia irritanH). Both sexes of 

 these last two species suck blood. 



Some fly larvae are important parasites of warm-blooded animals, 

 a condition known as myiasis. The horse-bots {G aster opMlus) live in 

 the stomach, throat, and nasal passages of horses. Cuterebrid larvae 

 live under the skin of rabbits and squirrels, and the well-known ox 

 warbles are larvae of Oestridae. Other oestrid larvae live m the 



