122 



THE AGRICULTURAL NEWS 



Ai-RiL 20. 1918. 



INSECT NOTES. 



THE WEST INDIAN MOLE CRICKET 

 OR CHANGA. 



{Concluded.) !i 



In the last issue of the Ai^rkultiiral SiWi some account 

 ■was given of the habits, life-history and enemies of the above 

 insect, aa observed in Porto Rico. The following notes are 

 concerned with some of the more important methods of 

 control used against the mole cricket in that island. 

 Control Measures. 



Control measures against the changa in Porto Rico 

 may be divided into preventive measures and repressive 

 measures. 



I'EEVENTIVE ME.\SURE.S. 



Among these may be mentioned the use of certain 

 mechanical devices and repellents, and the practice of certain 

 method.-s of cultivation and planting. 



Meckankiil Jtvurs. The writer states that it has long 

 been the custom among tobacco growers and market gardeners 

 in Porto Rico to wrap the roots of seedlings in the leaves of 

 mammee (Mam una omtrliana) when transplanting. Later, 

 when mammee leaves became scarce, their place was taken by 

 cylinders made nf tin, heavy paper, or wire. These cylinders 

 however are expensive, and those of tin and paper are found to 

 cause unnatural rooting conditions. These devices are no 

 longer practicable on a large scale, but a few will always be 

 used for valuable plants. 



Jiepelloits. These include Howets of sulphur and naph- 

 thalene flakes, but neither are effective in the case of a heavy 

 infestation of mole crickets. 



Planlin!^ methods. Sugar-cane is now protected from 

 the changa by planting in an upright or slanting position, 

 since this pest only attacks the eyes and the bases of the 

 young shoots. It has been found that hilling-up is some- 

 times u.seful in protecting gardens against the changa, 

 advantage being taken of the insect's aversion to making 

 its burrows up slopes, but this method is apparently inefJ'ec- 

 tive against a heavy infestation. Clean cultivation by itself 

 is not eti'ective against the mole cricket, but is useful when 

 preparing to apply a poi.soned oait. 



RE.MEliI.M, MEASURES 



These include ploughing, trapping ot various kinds, 

 flooding, and the use of p<)ison baits. 



Ploughing is valuable in controlling the changa, since 

 by this method the in.sects in the soil are turned up and 

 expo.sed to chickens, lizards, and other enemies. Further, 

 egg-chambers are broken up and some of the eggs are exposed 

 to the suD, and are thereby apparently prevented from 

 hatching. 



7>-rt///>/;-. The use of trap-lights against the changa 

 i.s only practical during the period that the annual tiif^hts 

 take place. In Portf llico the clianj<as tly in large numbers 

 in Oc ober, November, and December, and most abundantly 

 on damp, cloudy evenings. It is recommended that tjje trap- 

 light be very bright, and that the pan of oil and water placed 

 under it should be as large as possible. If only a small pan 

 is available, it is useful to have the changas that fall outside 

 the pan collected, since it has been found that the changas 

 are not attracted to the light it.self, but only to its vicinity. 

 It has aUo been found <)uite iinnece-ssary to keep the light 

 going after 10 o'clock. 



Experiments made with traps in Porto liico by sinking 

 wide-mouthed bottles in the earth up to the mouth were 

 found to give no result.s, even when baited with corn meal. 



It is stated that sacks or bags are used with good results 



in the. Isle of Pines as traps for mole crickets. The bags 

 are spread on the ground, examined early each morning, and 

 the mole crickets found under them are killed. 



F/oodiiii^ is useful wherever the position of the tields 

 makes water easily available. Nymphs and adults are not 

 killed even by a complete submersion for three hours, but 

 they usually find their way to the surface during that time, 

 being able to float, and although active swimmers they usually 

 fall prey to such birds as the heron. 



Poison tHii/s. Tliese have been found to be the most 

 successful upon small areas, such as garden plots. It is 

 essential that the land be cleared completely of all 

 vegetation, including even grasses, and kept clean for three 

 or four days before spreading the bait, and the crop may 

 be planted three to five days after the bait has been applied. 



It is stated 'that the most satisfactory bait yet found 

 is a dry mixture of 3 per cent. Paris green with cheap flour. 

 Flour of the poorest quality, even that ruined by weevils and 

 moths, is satisfactory for this purpose, corn meal, cotton-seed 

 meal, and bran making good substitutes, though flour seems 

 to be preferred by the changa. Barrett reported very .satis- 

 factory results from the use of a mixture of grass stems, 

 molasses, and Paris green. The Paris green and phosphorus 

 mixture used against crabs is said to be acceptable to changas 

 as well.' 



It is recommended that this mixture be applied, prefer- 

 ably in the late afternoon, at the rate of 300tt) to the acre, 

 and it may be spread broadcast over the land. This method 

 iias the further advantage of killing other injurious plant- 

 feeding insects, such as o'her crickets and cut worms. 



The Paris green and flour mixture may also be applied 

 in a shallow trench around the young plant at a distance of 

 an inch or more from the main stem, or it is suggested that 

 it may be introduced into a changa gallery where this 

 approaches the surface. 



It is advisable that fowls and domestic animals be kept 

 from access to poisoned mixtures. 



FLEAS AND THEIR CONTROL. 



As Dr. Shipley has remarked, the fact, now fully 

 established, that bubonic plague is transmitted by fleas, has 

 taken that wingless insect out of the category of those 

 animals which it is indelicate to discuss. A recently published 

 pamphlet {I-anmis' Hullitiii Si)j, of the United States 

 Department of Agriculture) by Mr. F. C. Bishopp, gives some 

 information of general interest about the life-history and 

 habits of various fleas, and the measures which should be 

 taken to control them. 



There are about 500 species of fleas known tn be in 

 existence, but the great majority of them need nut concern 

 us here, as they are parasitie on wild birds and mammals. 

 There are, however, some half a dozen species which are of 

 special economic importance as pests of man and certain 

 domestic animals. ^ 



Ilal'its. As a general rule it may be said that each 

 host has its own particular .sp-cies of flea; for instance, cats 

 and dogs are normally infested by the cat-flea (CU'iiocef'haliix 

 Jilis) and the dog-flea {Cteiioir/>/i<i/iis tain's), but these fleas 

 are sometimes a nuisance to man: again, the human flea 

 (/Wc.v irn'/iuis) is for the most pirt confined to man, but 

 may also be found on .some of the domestic animals; further, 

 rat fleas sometimes bite man, and if coming from plague- 

 infested rats can thereby transmit the bubonic plag'ie to 

 man. The Indian rat flea {.W /ioA.w/Ai ,7/,v//>/.\) and the 

 ICuropean rat flea (i'lnUofihyllns Josiio/its) are the two 

 species responsible for the spread ol the plague in variou 



