186 



THB AGRICULTURAL NEWS. 



Juki U. 1919. 



INSECT NOTES. 



THE EUROPEAN OORN 'BORER 

 {PYRAVSTA NUBIALIS, HUBNER). 



Thf European corn borer is a recent introduction into 

 the United States It appears to have entered the country 

 through the port of Boston, for it is in the vicinity of this 

 city that it is established Here it has been known since 

 July 1917, but it was introduced some four or five years 

 before that, according to Entomologistswho have investigated 

 this insect. From what has been learned already of its 

 habits, food-plants, and distribution, it is believed that the 

 European corn borer is one of the most serious insect pests 

 yet introduced into the United States. 



At the annual meeting of the American Association of 

 Economic Entomologists, held at Baltimoie, Maryland, 

 on December 26 and 27. 1918, a paper was read on the 

 European corn bnrer by Mr. D. J. Cafifery. This paper 

 appeared in the fournal of Economic Entomology (Vol. XII, 

 page 92), together with a report of the discussion which 

 followed, and there are two further notes in the same 

 number of the journal on this insect, at pages 124 and 

 132. The information given herewith is abstracted from 

 the sources mentioned. 



Tlie discovery of this insect in Massachusetts in 1917, 

 was made by Mr. S- C. Vinal, who in December of that 

 year reported that it was distributed over an area of about 

 100 square miles in the vicinity of Boston. Large quanti- 

 ties of raw hemp are annually imported into this district, 

 and as hemp is one of the favourite food-plants of this 

 insect in Euiope, it is suggested that this may be the 

 medium through which the introduction was eflfected. 



The species is recorded as being widely distributed 

 in Central and Southern Europe, and in Northern Asia, 

 China, and Japan. Corn, hemp, hops, and millet are the 

 principal ccfinomic plants attacked by the pest in the Old 

 World, and a loss of 50 per cent, of the crops frequently 

 results from its depredations. 



Prior to its discovery in July 1917, the Europpan 

 corn borer had never been recorded in the United 

 States. A more complete survey of the district revealed 

 that in November 1918 it occurred in thirty five 

 towns of Eastern Massachusetts near Boston, distributed 

 over an area of some 320 S()uare miles. Since that time it has 

 been discovered in the vicinity of Schenectady, New York, 

 over an area of about 400 square miles. This infestation is 

 estimatcil to be of about two years' stan'ling, and is stated to 

 be decidedly Ipss severe than that near Boston. 



The principal food-plants of the European corn borer in 

 MassachaiettB are the- varieties of corn — sweet corn, field 

 oorn, and fodder corn. It also attacks a considerable number 

 of vegetables garden flowering plants, and several of the 

 larger grasses and weeds. 



The moths from the over wintered larvae emerge about 

 the first week in June and deposit their eggs generally on 

 the under surface of the foliage of the food-plant. 



This insect passes the winter as full-grown or nearly 

 full-grown larvae within their tunnels io the food-plant. 

 There are two complete generations of the insect each year, 

 and individual females in each generntion deposit an average 

 of 3.50 eggs. At the present time, there are practically do 

 parasites or other natural enemies of this insect in its new 

 localities, and consequently its rate of increase is very rapid. 



The female of this species is capableof flight, and the infes- 

 tation may be spread by natural means, but the transportation 

 of infested plant material provides the principal element of 

 this danger. Sweet corn, or roasting ears, green cornstalks an 

 feed for cattle, dry corn stalks used as packing material, and 

 ripe corn on the cob are all capable of transporting the 

 insect from infested to uninfested districts. 



The Federal Horticultural Board has issued a quarantine 

 order which prohibits all interstate movements of all corn 

 fodder, corn .stalks, whether used as packing or otherwise, greai 

 sweet corn, roasting ears, corn on the cob, and corn cobs, from 

 all towns within the area infested by the European corn borar. 



'If corn were the only plant attacked by the European 

 corn borer, the problem of restricting the spread of the 

 insect would be comparatively simple, but several of the 

 other host plants present openings by which the pest may be 

 transported through the ordinary avenues of trade. 



'In badly infested areas the larger larvae of tie Euro- 

 pean corn borer frequently leave their original host, whether 

 it be corn or some of the weed or grasses, and enter other 

 plants growing in tlje vicinity. This change of habitat is 

 generally due to the fact that the food supply in the original 

 plant has been exhausted. Under the.se circumstances, the 

 larvae may attack and enter almost any plant growing. in the 

 vicinity, and possessing a moderately soft and succulent stem. 



' In home gardens, and in market areas it is a common 

 practice to grow several crops together, or inter-rowed in the 

 same area. Sweet corn is almost always included among 

 these crops, and serves to attract the ovipositing females of 

 the European corn borer. After the food supply in the corn 

 plants has been exhausted, the larvae enter other plants. In 

 this manner the larvae frequently infest celery, Swiss chard 

 spinach, beans, potatoes, tomatoes, and some of the flowering 

 plants, including dahlias, gladiolus and chrisanthemuma.' 



The discussion which followed the reading of the paper 

 revealed that the Economic Entomologists pre.sent at the 

 meeting viewed the situation with grave concern, and felt 

 that the most thoroagh con'rol and quarantine measures 

 should be adopted to prevent the spread of the insect. At 

 the time of the meeting the Mas.sachusetts infestation 

 was the only one known; the occurrence of the insect io 

 New Vork was discovered and reported at a later date. 



The prospect of this insect, which was considered the 

 most serious pest of corn, invading the com growing areas 

 in the Central and Wesi Central States where all the staple 

 crops —corn, wheat, oats and kafirs would be liable to 

 attack, and where enormous tracts of land are purely 

 agricultural, was taken as a prospect of the most serious 

 nature. 



Any measures looking toward the control of the 

 European corn borer, and ite limitation to the area now 

 occupied, must consist of thi destruction of infested plants 

 within that area, supplemented by quarantine measares to 

 prevent the dissemination of the species through the 

 transportation of infested material. 



This insect is a relation of the nsoth borer of tbt 

 sugarcane, so well known in the West Indies. They 

 belong to the same family (Pyralidae) of the Lepidoptera 



