November 14, 1890.] 



SCIENCE. 



269 



light may have to be kept on for several days, and, unless 

 the storage capacity were great, a man would be required 

 specially to work the retorts. Now, since oil-burners are 

 pronounced practically equal to gas for revolving lights, 

 while for fixed lights a great power is not required, it is 

 probably better economy to multiply lighthouses than to in- 

 crease the outlay on those existing. Besides, the limit of 

 the power of oil-lamps has certainly not yet been reached, 

 and, urged by the rivalry of gas, it is certain that we shall 

 get more powerful burners. Even before the South Fore- 

 land experiments were concluded, new and more effective 

 types of burners had been constructed. In places where 

 both light and power are required, as at Ailsa Craig 

 where there are siren fog-signals in addition to the light- 

 house, gas is pretty certain to be adopted in the future, as it 

 simplifies the attendance on the light, and is always at hand 

 to start the air-compressing machinery in case of sudden fog. 

 The production of gas by the distillation of petroleum is so 

 simple that it can easily be learned by the class of attendants 

 employed in lighthouses, and does not sensibly increase the 

 chance of a break-down. It is a pity that the most interest- 

 ing quality of gas-illumination, that of sky-flashing, was not 

 more fully investigated. This seems to be full of promise. 

 Often the thickness of a fog, measured vertically, is very 

 small, and an intermittent light projected on to the sky could 

 be readily seen Every one knows how the attention is 

 caught by sheet or summer lightning, ia whicV the arch of 

 the sky is momentarily lit up by a flash which is below the 

 horizon, and therefore out of the range of direct vision. 

 Even if the observer have his back to it, he can scarcely 

 fail to see it According to Sir L. McClintock, something 

 of the same effect can be produced by a sudden burst of 

 flame, produced by turning gas on for a moment before 

 it is lighted. The condition of a mariner groping his 

 way up channel in a thick fog is so dangerous that every 

 expedient that promises to aid him is worth investigation. 

 There are sufficient lighthouses where gas is used to enable 

 this to be tried with scarcely any expense. 



THE ARMY-WORM IN MARYLAND. 



In accordance wilh Professor Rilev's instructions, on May 31, ac- 

 companied by Mr. Albert I. Hay ward of the Maryland Agricultural 

 College, Mr. William H. Ashmead started for Salisbury, Wicom- 

 ico County, and Princess Anne, Somerset County, Md., to make 

 such observations on the army-wotm (Leucania unipuncta), then 

 depredating in tlie vicinity of these places, as the limited time at 

 their disposal should permit. 



During the journey (reported in the September bulletin of the 

 United States Department of Agriculture) they ascertained in 

 conversation that the worms were most numerous in the immedi- 

 ate vicinity of Princess Anne, and so they took the most direct 

 route for that place. 



As thfy approached their destination they began to see the ef- 

 fects of the worms' work. Just before entering the town, they 

 passed by a large field of corn, owned by Mr. H. H. Deshields, 

 containing about twelve acres, that bad been devastated by the 

 army-\^orm, and only a few green plants could be detected here 

 and there in the field. 



This tield was in marked contrast with another corn-field adja- 

 cent, which had been saved fiom attacks by ditching, as recom- 

 mended in the " Third Report of the United States Entomological 

 Commission." Another thing observed was that this field was 

 flanked behind wilh a wood that evidently prevented their ingress 

 that way, whereas the former was contiguous to grass and wheat 

 fields, in which the worms are said to originate. 



Just before entering the town, another ten-acre corn-fleld was 

 passed, owned by Mr. John L. Lornier, that but a short time pre- 

 viously presented a most promising appearance, but which is now 

 completely " cleaned out " by the worms. It may be worthy of 

 record, as the theory has been advanced that insects originate in 

 just such places, that in an adjoining field were three old hay- 

 stacks. Contrary to their expectations, they found the reports of 

 their numbers not at all exaggerated ; and the damage done is 

 even worse than was anticipated, the wheat, corn, barley, and 

 timothy of many of the fanners being totally ruined by them. 



One of the most interesting places for observation visited was 

 that of William J. Porter, a practical and energetic farmer, who, 

 although he hiis fought the worms most vigorously, has suffered 

 severely from their attacks. By means of ditching and by burn- 

 ing straw, he has been able to save part of his crops; but several 

 of his fields of corn, timothy, and wheat were already ruined. He 

 reported the worms much less numerous than they had been, but 

 there were many thousands seen in his fields. 



During their rambles Mr. Porter took them to one of the 

 ditches he had dug to keep the worms out of a large corn-field. 

 In this ditch he had sunk, every two or three yards apart, deeper 

 pits, where they foimd the worms two and three inches deep; and 

 the rest of the ditch was black with the dead and living worms. 

 From the dead a fearful stench arose in such strength as to at- 

 tract the buzzards, which were proudly sailing overhead. Vari- 

 ous carrion- beetles, too, seemed to revel in the carnage. Large 

 silphids and staphylinids, besides numerous smaller forms, were 

 quite numerous; while the hard-shelled histerids wei-e quite plen- 

 tiful, working through the putrid masses. Several carabids were 

 observed running through the ditches, preying on the living and dy- 

 ing; Scarites subterraneus Fabr. being particularly noticeable, and 

 no doubt, with its large mandibles, doing efficient service in de- 

 stroying the worms. 



Mr. Porter informed Messrs. Hayvvard and Ashmead that the 

 worms always originated in the wheat and old grass fields, and 

 during the morning hid themselves from observation, never ap- 

 pearing in numbers until after three o'clock p m , which accorded 

 with their own observations and with those of the other farmers 

 visited. 



They ate up the timothy and corn clean, and, after devouring 

 the blades of the wheat, congregated, three or four together, on 

 the heads. After devouring several of the lower grains, they ate 

 the husks and nipped off the upper portion of the kernel of the 

 rest, thus almost entirely destroj'ing it. If the grain is well ad- 

 vanced and somewhat hard, it escapes destruction; but, as most 

 of the wheat visited was still in the milk, the destruction was 

 great, and not less than 75 per cent of the crop had been already 

 destroved. 



Although several parasites are known to prey upon the worms, 

 and a sharp lookout was kept for such, none were seen except a 

 few cocoons of an Apanteles, which were discovered, together 

 with the worms, under old trash and logs in a wheat- field. A 

 few were gathered and forwarded to the Department of Agricul- 

 ture, some of which have since hatched, and prove to be Apan- 

 teles militaris Walsh. 



The corn-fields of all this region were found to be badly infested 

 with the larvae of two species of beetles; and so numerous are 

 they at times as to entirely destroy the first planting, and necessi- 

 tate a replanting of entire fields. T.'ie farmers call them the 

 " bud-worm,"' and do not seem to be aware that they are two dis- 

 tinct species that do the injury. 



One species is a well-known corn-pest, the larva of Diabrotiea 

 vittata, widely distributed over the United States; the other is 

 one of the wire-worms, possibly the larva of a common beetle, 

 Drastarius elegans Fabr., which also has an extended range, ex- 

 tending into Mexico. So far as known, this latter species has 

 never before been reported as injurious to com, as the larva is 

 supposed to be predaceous on other insects. It may, though, have 

 dual habits, not an unusual occurrence in some insects. Both of 

 these species are more prevalent in low fields, the higher fields 

 being less subject to their attacks. 



Another beetle, found to be seriously injurious to cantaloupes 

 and sweet-potatoes in this region was a chrysomelid, Systena 



