272 



TlPULID.E.- 



-INSECTS.- 



-CErii^n:\iTiA. 



Okdee — DIPTERA. 



An order of two-winged insects, constituting one of 

 tlie most extensive gronps amongst the Annulosa. 

 Although, strictly speaking, they are only two winged, 

 yet they have, as it were, two abortive wings behind 

 the true pair ; these are commonly called haltcres 

 or balancers; they are frequently kept in rapid motion, 

 whilst the true wings are apparently quiescent, and 

 by this rapidity of motion cause a loud piping noise; 

 this is particulaily observable in the genus Sericomyia. 

 Diptera are usually of moderate size, the largest known 

 being a species of Acanthomera from Mexioo^about 

 one inch and three-quarters in length; the majority are, 

 however, small insects. 



Individual species are sometimes extremely abundant, 

 so much so as in some instances to become a plague 

 and a nuisance. Some of the species may be called 

 domestic, the house-fly being an example. Flies have 

 in all ages attracted observation from the numbers in 

 which they sometimes appear, and in others from the 

 terror they excite by their well-known power of causing 

 the most intense annoyance both to man and animals. 

 One of the plagues of Egypt was a " swarm of flies," 

 probably mosquitoes, which came from the banks of 

 the muddy Nile. Flies have no mandibles (jaws), but 

 are provided with a proboscis and also several lancet- 

 like organs. The common gnat {Culex pipiens) has the 

 parts of the mouth produced into a slender rostrum, 

 half as long as the insect ; the males have beautiful 

 plumose antennae. The approach of the gnat is known 

 by its shrill hum ; but its alighting on the face or other 

 uncovered part of the skin is so light as not to be easily 

 perceptible ; it instantly pierces the skin with its fine 

 lancets; these, it pushes by degrees quite in to their base, 

 and while the creature imbibes its fill, it apparently 

 envenoms the wound, which subsequently causes the 

 most painful irritation. Records of their appearance 

 in immense hosts in particular localities, even in this 

 country, are not wanting; thus we are told, that in 1736 

 they appeared at Salisbury in such hosts as to resemble 

 columns of smoke ; and in 17G6, in the month of 

 August, they accumulated in incredible numbers at 

 Oxford, resembling a black cloud, almost totally inter- 

 cepting the beams of the sun. Such appearances are 

 not imcommon in Suffolk and Norfolk, as I have been 

 informed by residents in those counties ; on such occa- 

 sions their torment is beyond description terrible. 



Neither heat nor cold seems to ali'ect these tormentors 

 of the human race. In Lapland they swarm in in- 

 credible hosts during certain periods of the year ; there 

 is neither rest nor sleep for the inhabitants, indoors or 

 out, unless the body is smeared with some unguent, such 

 as grease, tar, or oil. In the eastern part of the world 

 we well kuow that mosquitoes are a plague by day, and 

 a " terror by night." Other species, belonging to the 

 family TipuUda', are well known for the loss occasioned 

 by their attacks on grain crops. The Cccidomyia tritici 

 (fig. 171) deposits its eggs in the corolla of the young 

 wheat plant, in which the larvae are hatched, and by 

 their ravages frequently cause a considerable loss, if not 



an entire destruction of the crop. In North America 

 the ravages of the grain crops at times spread to an 

 alarming extent. In Fitch's " Report of the noxious 

 insects of the state of New York" are detailed accounts 

 of their ravages; the larvae of several genera are equally 

 destructive. Species of the genus Chloropa have long 

 been known seriously to injure crops. Linnaeus men- 

 tions one, Chlorops Frit, which infests the heads of 

 barley, causing an annual loss of not less than half a 

 million of dollars annually in Sweden. The species of 

 the genus Chlorops have, as the name indicates, green 



Fig. 171. 



a Cecidomyia tritici. SThe same, natural size. cTlie cocoon of tlie fly. 



d Antenna of the ra.ile. e An ear of wheat attacked by it. 

 /A grain of wheat attacked by it. g The American Chinch— Bug. 



eyes, and may be seen frequently on the young heads 

 of grain crops in the spring ; but we must refer the 

 reader to the work above alluded to, for a detailed account 

 of the enormous loss occasioned to the farmer through 

 the destructive agency of these minute depredators. 



No destructive insect belonging to the family Diptera 

 is better known than the species popularly called Daddy- 

 long-legs {Tipula oleracca). This species, and some of 

 its congeners, occasionally prove by their numbers ex- 

 ceedingly destructive in the larva state by feeding upon 

 the roots of grass, and thereby doing great mischief; 



