346 



THE AGRICULTURAL NEWS. 



October 31, 1908. 



INSECT NOTES. 



Diptera. 



{Concluded from the last i^sue of the Aiincnliiiral Xi'inf.) 

 The family iluscidae includes the house-flies, the flesh- 

 flies, and the parasitic Tachina flies. 



The common house-tlie's (Maxfn (/i<///'.v^/'-,() ;nc extiemely 

 abundant and very important. They are world-wide in their 

 distribution, and are important factors in the distribution of 

 certain diseases, such as fyiihoid lever. The eggs of the 

 house-fly are laid in horse 'iuanure or other excrementitious 

 or decaying matter. The eggs hatch in a few hours, and 

 the larvae become full-grow'n in five or six days, and after 

 about five days in the pupal stage; the adult fly emerges. The 

 best means of controlling this insect is by doing away with 

 its breeding places. All decaying matter and filth should be 

 kept cleared away, and hor.sV; manure should be removed from 

 stables regularly at peri<idsof not more than four to five days. 

 The ^luscidae also int''lude tlie blue-bottles and blow- 

 flies. The most important of these in the West Indies 

 is the species known as the Screw worm (Coiiipxoiiii/ia 

 macellaria), w-hich a feW' years ago was so abundant in 

 St. Lucia. This insect is! especially dangerous on account 

 of the habit of depcsiting eggs in sores or wounds in the 

 flesh of man and beast, and sometimes in the nasal passages 

 of domestic animals and human lieings. In a })amphlet pub- 

 lished by the Imperial Department of Agriculture (Pamphlet 

 Series No. 1-f) the life-history of tliis tiy is given, with an 

 account of its attacks (nil domestic animals at St. Lucia, 

 and of the remedial ti'eatment that sliould lie employed in 

 case of attack. 



The Tachinidae or Tachina flies are parasitic in their 

 habit, attacking caterpillars and other insects. The eggs are 

 attached to the skin of the host insect, and the maggots 

 burrow through the skin, and live on tlie liody contents. The 

 host is entirely devoured, and insteail nf a moth or butterfly 

 developing from sueli a pariisitized insect, a c'onsiderable 

 nundiei- of Tachina flies is obtained. 



It may be <lue to flies of this group that the potato worm, 

 which .sometimes seriously attacks the leaves of sweet j)otatos 

 in these islands, is so completely checked. 



The Sarcophaginae are the flesh-flies, the larvae nf which 

 live in or on flesh. One of these, Surcujiliaiju. tiii'iltdtn, 

 aUacks the c<itton worm. 



The Siplionaptera or Fleas. 



The small insects known as fleas arc lilood-suckmg 

 parasites which were urilil recently ('hxssified as a family 

 of Diptera. Of late yeaVs, tlu'y iiave more often been 

 jfiven the rank of a natural order under the name of 

 SiphoiKiptera. About 150 species are known, and 

 these are parasites on man, and on ilojrs, cats, and 

 fowls iunong the domestic .mimals, and on rats and 

 a number of other wild animals. 



The fleas are wingless ; the liody is compressed latt'rally ; 

 the in<nith jiarts are adaptc(l for piercing and blood sucking. 

 The hind pair of legs arc developed spi>cially for jumiiing. 



The head of the fleas is small, and the body is set with 

 stiff hairs. The larvae are'sinall, slender and footless, but on 

 account of the shape of the liead. are more like beetle grubs 

 than th(^ maggots of tlie Diptera. 



AFost pe()ple are familiar with the appearance of the 

 adult flca.s, l)Ut very few khow the larvae. They seem to live 

 on dry vegetable dust and on organic waste matter, and the 

 length of lif^ of the li\rytie .seems tn vary undi'r different 



conditions. In the case of tlie cat and dog flea, which is one 

 of our commonest specnes, it has been stated that the larval 

 stage varies from (Sge to two weeks, while the wlxile life 

 cycle from the de[)0!Stion of the egg to tlie appearance of the 

 adult is sometimes completed in a fortnight. 



The jigger i\ci\.JSarcops////ii pcnetranx) is fairly common 

 in the West Indies, and in other tropical and subtropical 

 places. This is tlie flea which burrows into the skin. 

 It attacks many domestic animals, and is said also to attack 

 birds. These fleas attack man generally about the feet, 

 and the swellings, , produced as a result of the irritatiim 

 caused by the insect, and by the swelling of the body of the 

 flea in which the eggs are developing, are very painful, and 

 .sometimes produce tiprious results. Whenever these in.sects 

 :ir.' di.scovered in thg skin they should be removed at once, 

 and great care .shoulil be exerci.sed not to burst the body of 

 the in.sect allowing' the eggs to esca[)e. (See Ai/)irii/finii/ 

 Xew.'i, Vol. VI, p."l70.) 



The house flea (I'lilct irritaiix) attacks man, and is 

 known in all [larts of the world. In some countries it is 

 a serious jiest The'eggs of this insect are de])osited in the 

 dust on the floorsiof houses, or under carpets, mats, etc. 

 The eggs of the cat and dog flea (Pidc.i xrrrn.tiri'/if:) are 

 deposited among the hairs of an infested animal. These drop 

 to the floor and hatch there, and the larvae live among the 

 dust and organic ]Ki,rticles in the same way as the house flea. 

 A considerably amount of interest attaches to fleas on 

 account of the rece(it discovery that these insects are respon- 

 sible for the Iran.smission of plague. It has generally been 

 stated that the rat flea is the carrier of plague from the infected 

 rat to the human ^victim, but recent experiences .seem to 

 indicate that other species may he as much concerned as the 

 rat flea. During the recent occurrence of plague in San 

 Francisco, fleas were collected in the plague laboratory and 

 hospital, and in the'-refugee camps. 



The following statement is (|iioteil from an article : 

 ' Notes on Fleas colh^'tetl on rat and human hosts in San 

 Francisco and elsewhere' by II. W. hoarie, Stanford 

 University, California, whirh ^ippcaied in ihe ('ninnlimi 

 Eii/oiiiDto'iixt for August last ; — 



'A study of' these records shows tliat t.in lufjixijlla 

 fhiojiix, which is known as the ])lague flea in countries where 

 the disease is epidemic, is we'll established in San Frauci.sco, 

 and is siireading to neighbouring citie.s Doubtless a .-.earch 

 would reveal it in many localities. It is interesting to note 

 that out of the iu'i fleas taken from the human beings, some 

 of them pel-sons who were sick, or had died of the plague, from 

 attendants ill the hospitals, and from men engaged in catching 

 the lats, not a single L()< iiiiipai/Ud chi'ojiin was found. On 

 till' other hand, Piflcr irritdiis, wliich is the most common of 

 the liuniau fleas, has been found iplite abundantly on rats. 

 One lot sent from l)r. Kucker contained eighty-one specimens 

 of P.in-itdiix, and bo other species. Tiie.se were collected from 

 eighteen rats taken in houses and sewers in infested districts.' 

 In view of the fact that plague is now known to occur 

 in the American tropics, great care should be taken to })re- 

 vcnl fleas from liecoming too unmerous in houses. The free 

 use of pyrelhrum on dogs and cats, and on the floors, especially 

 wliere these iwiimals sleep, >M>uld be very u.seful in this con- 

 nexion. Floors should be frei|uently and thoroughly swept, 

 carpets and nigs sJiould be taken out and aired and beaten 

 at frequent intervals. In a recent number of (he A;/)ii-ithiirii/ 

 Xeifs {\'ii]. ■\T1, J). 13) two flea remedies are given, lu mie of 

 these the free use of pulverised alum is reeommeiided, and in 

 the other the use of soap suds in a plate on the floor, with 

 a flame burning iri the middle. The flame attracts the fleas, 

 and they fall intolthe soaj) suds and ari' killed. 



