106 



THE AGRICULTURAL NEWS 



April 6. 1918. 



INSECT NOTES. 



THE WEST INDIAN MOLE CRICKET 

 OR CHANGA. 



An account of the West Imlian mole cricket (Scapterisais 

 via'nus) has recently been issued by the Porto Rico Agri- 

 cultural Experiment Station under BtiUctiii Xc 2J by >fr. 

 R. H. van Zwaluwenburg. Since the above species or closely 

 related species of mole crickets occur as pests of vegetable 

 garden crops and of grass lawns in some of the other West 

 Indian islands, it may be useful for readers of the Agrkii /tura/ 

 A\u's to have a brief descrijition of this insect and of some 

 of the control measures used against it in Porto Piico. 



This mole cricket is commonly known as the 'changa' 

 in Porto Rico, a name derived, according to the writer, from 

 the fancied resemblance of the insect's head to that of 

 a monkey (chango). This cricket is considered to be the most 

 serious insect pest of general agriculture in the above island, 

 and has been the subject of investigations extending over 

 a number of years. '• 



DISTRIBOriON. 



The writer states that the fitst mention of this insect as 

 a pest appeared in 1836, in letters from A. McBarnet of 

 St. Vincent, who described the cricket as injurious to pastures 

 and to cane plantings. Althnugh the pest is named only as 

 the 'mole cricket', the insect in question is without doubt 

 this species. 



This cricket has usually been known in literature under 

 the name of Stapfcrisciis duladylits, but Jidai/yhis is 

 apparently limited in its distribiltion to parts of South and 

 Central America, whereas S. I'h-ii'iiis has a wider distribution, 

 being found in the south eastern L nited States, the West 

 Indies, and portions of South America. The present known 

 distribution of the 'changa' (S. I'ki/it/s) is given as follows: 

 Georgia, Alabama, Florida, Cuba, Haiti, Costa Rica, Panama, 

 Porto Rico, Culebra Island (P. iJ.), St. Croix, St. Vincent, 

 St. Lucia, Trinidad, Barbados, French and Dutch Guiana, 

 Brazil, Uruguay, Argentina, and Peru. 



Fk;. 2. MoLK Cricket 

 ■ Seen from above and from the side. ( U S. Dipt. Agric.) 



lI.VlilTS.i 



The mole cricket is mainly an underground insect, .since 

 all its stages of development arc spent in burrows, which it 

 rarely leaves, and then generally at night. This in.sect is 

 never found in heavy clay lands in I'orto Uico, but in light, 

 loamy hoils, which admit of easy 'tunnelling, whereas the 

 difliculties of burrowing in heavy soils would be too great' 

 The changa usually avoids tunnelling on very sloping land, 



and works mostly on level areas. It was observed that this 

 cricket is influenced by moisture changes, since in the dry 

 season its burrows are carried to a depth of some 12 inches 

 while during the rainy .season they are to be found usually 

 within 4 inches of the surface. In Porto Rico a prolonged 

 drought often causes an overland migration of adults and 

 nymphs at night to more favourable breeding and feeding 

 grounds. 



The mole cricket has its forefeet powerfully develoi)ed 

 and well adapted for digging, while the hard rounded shield 

 behind the head is suitable for shaping and compressing the 

 soil which forms the sides of the tunnel. The changa, in spite 

 of its clumsy movements, due to the weight of its fore-legs, is 

 a rapid runner, even over the surface of the ground, where 

 it often increases its speed by short hops. In its under- 

 ground tunnels it is able to progress very rapidly, moving 

 forward or backward with equal ease. During the early 

 stages this insect is Very active both in jumping and running, 

 but it Was noticed that in the later stages the power of 

 jumping is lost, and in its efforts to leap the insect often 

 turns a somersault in mid-air. 



The adult is a heavy, clumsy Hicr, landing heavily after 



a long swoop. It is not an uncommon occurrence in Porto 



Rico for adults to fly into lighted houses during the early 



evening frrm dusk onwards, especially on damp cloudy nights. 



FEi;r)iN(i ai.vBiTs .\xd food pl.\nts. 



The changa is priknarily a vegetable feeder, only occasion- 

 ally indulging in animal food. It remains underground and 

 feeds from below, and almost an^' young plant growth is 

 attacked. A seedling may be partially gnawed through at 

 its base, or in the case of tender growths almost the whole 

 sprout is pulled into the soil and eaten. 



Of the crops of economic importance tobacco seems to 

 be the one that sutl'ers most from the changa in Porto Kico, 

 but the use of a poisoned bait (Paris green and flour) has 

 lessened the damage done to this crop. 



Sugarcane is attacked when planted on Idose or sandy 

 soils, the injury beiug>>conlined to the germinating seed and 

 to the bases of the young shoots, which are partially gnawed 

 through. I 



Most garden crops, such as corn, tomato, cabbage, lettuce, 

 and pepper, arc severely damaged by the changa. Grasses 

 of all kinds serve as food for this cricket, Paspalitm sp. and 

 Ekusinc iiulica being the favourites among the common wild 

 species. Damage is also done to the roots of any plants that 

 happen to be encountered by this insect in the course of its 

 tunnelling. 



LIl'lvIllsTOKV. 



The life-history was worked rut under laburatory 

 conditions, but the writer is of (i[)inion that it does not seem 

 probable that the results so obtained differ very much from 

 the actual life-cycle umler natural conditiors, except that in 

 nature the developmental stages are probably shorter than 

 in the insectary. 



Ei:;g. The gray, oblong oval, shiny eggs are laid in an 

 oval chamber about \\ inches long, 1 inch high, and 1 inch 

 wide. According to the observations of the writer this 

 chamber is a blind pockyt leading off from one of the galleries, 

 and its entrance is concealed by a picking of loose earth 

 after the eggs are laid, Which serves to protect them from 

 nymphs or adults. The eggs are dropped by the female in 

 a loose heap. It was found that under laboratory conditions 

 the egg stage averaged about nineteen days. 



Later s/ii'^cs. After hatching the young changa is very 

 active and begins feeding almost immediately. During the 

 first few days of its life the changa exhibits a cannibalistic 

 tendency under insectary conditions, but cannibalism is not 



