Decbmbbb 4, 1919. 



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The Florists^ Review 



23 



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FIGHTING FERN FOE 



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FLORIDA FERN OATEBPILLAB. 



Devotes Itself to Ferns- Only. 



The Florida fern caterpillar is a na- 

 tive of Florida and tropical America. 

 But, alas, greenhouse conditions any- 

 where are suflBciently tropical to suit it 

 to a nicety and it makes itself thorough- 

 ly at home in northern fern houses, 

 causing great loss to the growers, as 

 several of The Eeview's subscribers re- 

 cently have testified. Ten or fifteen 

 years ago it appeared in large numbers 

 in the more northerly latitudes, notably 

 in the District of Columbia, Ohio and 

 Illinois. One grower, after a disastrous 

 experience with the pest, pronounced it 

 the fern grower's worst enemy and ad- 

 vised that the introduction of the insect 

 be sedulously avoided by using extreme 

 care in the purchase of ferns. 



The fern caterpillar seems 

 to be fastidious in this one 

 respect, that it usually will 

 eat nothing but ferns and 

 it prefers the tenderest of 

 the leaves, especially the 

 growing tips of young 

 fronds. The entomologists 

 of the United States De- 

 partment of Agriculture say 

 that the depredations of the 

 insect "are apparently re- 

 stricted to ferns.'-' 



doom the plants unless the swiftest and 

 most effective remedies were used. 



Many experiments have been tried in 

 the effort to find a satisfactory means 

 of combating this pest. One authority 

 states that "the regular burning of to- 

 bacco papers, about twenty-five sheets 

 to a house 30x100, will destroy the moths, 

 which fly only at night. ' ' He also states 

 that the same treatment will kill some 

 of the smaller worms, but that the larger 

 ones must be hand-picked. 



How One Firm Conquered It. 



Albert C. Oelschig, of Savannah, Ga., 

 related some weeks ago, in The Eeview, 

 how the pest was completely subdued 

 by his firm. "For a number of years," 

 said Mr. Oelschig, "we found it prac- 

 tically impossible to grow ferns, on ac- 

 count of the fern caterpillar, which was 

 brought to our place, we think, on some 



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Its Destructiveness. 



But it is a glutton in re- 

 gard to its one article of 

 food. Nay, it is worse than 

 a glutton, for it habitually 

 "bites off more than it can 

 chew." The entomologists 

 say again: "Though not 

 closely related to the true 

 cutworm, it has the same 

 habit as cutworms of cut- 

 ting or severing portions of 

 the fern plants, apparently 

 destroying more than it re- 

 quires for food." So it is 

 true to its name; its United 

 States headquarters are in 

 Florida and its food is 

 ferns. 



The Latin name of the 

 insect, according to government ento- 

 mologists, is Eriopus floridensis. It is 

 also known as Eriopus elegantulus and 

 Callopistria floridensis, and it is fre- 

 quently referred to as the southern fern- 

 cutworm. The larva — that is, the cater- 

 pillar itself — varies in general color from 

 apple green to velvety black, and when 

 full-grown it is comparatively large and 

 conspicuous, being about one and three- 

 eighths inches long. Its parent, the 

 moth, ia about half an inch long and 

 has a wing expanse of one and one- 

 eighth inches. 



It is stated by some growers that 

 when a greenhouse is badly infested 

 with this caterpillar, its presence can 

 be detected by means of a peculiar, 

 heavy, sweetish odor, which permeates 

 the entire atmosphere of the house. But 

 it is certain that so noticeable an odor 

 would indicate that the insects were ex- 

 tremely numerous — so numerous as to 



The g^reatest enemy the 

 fern grower has," is the way 

 one grower characterizes the 

 Florida fern caterpillar. ''One 

 experience will satisfy him 

 that an ounce of prevention 

 will save hundreds of plants if 

 used at the right time." 



Boston ferns obtained from Florida. But 

 at length we discovered a real remedy. 

 We found that we could clean up this 

 pest by simply spraying with nicotine 

 extract to which fish oil soap had been 

 added. Our method is to dissolve seven 

 or eight pounds of the fish oil soap in a 

 barrel of water. Then, in diluting the 

 nicotine to the proportions prescribed 

 on the can, we use one-fourth soapy 

 water from the barrel and three-fourths 

 clear water. When we spray this on 

 the plants, the soap makes the nicotine 

 stick and it does the business. This is 

 another case in which prevention is bet- 

 ter than cure. Now we spray our fern 

 houses every week or ten days, even 

 though there are no fern caterpillars 

 there. The spray will destroy the pests 

 only in certain stages of their life cycle. 

 Hence, when a greenhouse is badly in- 

 fested, repeated applications are neces- 

 sary to clean them out," 



Several years ago the United States 

 Department of Agriculture, after con- 

 ducting a series of investigations on the 

 subject, issued a bulletin which con- 

 tained a detailed description of the 

 Florida fern caterpillar and suggestions 

 about the control of the pest. The gov- 

 ernment entomologists seemed inclined 

 to give their verdict in favor of hand- 

 picking, but added that fumigation with 

 hydrocyanic acid gas might be effective 

 if properly performed. The latter form 

 of treatment, however, does not appear 

 to have been fully tested. 



The moth of this pest, says the gov- 

 ernment bulletin, belongs to a group of 

 noctuids in which the forewings bear at 

 the sides, above the middle, a project- 

 ing area or tooth. The hind-wings are 

 rather broad and well rounded at the 

 sides. The thorax and abdomen are 

 wide, the latter especially so in the fe- 

 male. The color of the fore- 

 wings is pale brown, marked 

 with white scales, forming a 

 peculiar and attractive pat- 

 tern. The hind legs are dull 

 buff, edged with dusky 

 brown; the lower surface is 

 paler. 



Would You Recognize It? 



The larva, or caterpillar, 

 the bulletin continues, is 

 slender, with forelegs and 

 prologs normal and well de- 

 veloped. The head is small, 

 wider than long, greenish in 

 life, or pale yellow in in- 

 flated specimens, with the 

 V-mark strongly marked. 

 While this species is ex- 

 tremely variable in general 

 color, there is one charac- 

 teristic mark which extends 

 transversely across the an- 

 terior border of the thorax 

 in a blackish line and 

 abruptly backward under 

 the spiracles to the second 

 thoracic segment, and some- 

 times nearly to the anal seg- 

 ment. The thoracic plate is 

 about twice as wide as long, 

 and not strongly marked. 

 The general color varies from yellow 

 to bright green to dark, nearly black. 

 In the palest form the thoracic border 

 may extend nearly to the third joint of 

 the thorax and then cease, or reappear 

 in short, longitudinal dashes just below 

 each spiracle. In the forms which are a 

 little darker these lines are more pro- 

 nounced, and similar transverse dashes 

 mark the dorsal surface of the last three 

 abdominal segments. In the more strong- 

 ly marked form, these transverse bands 

 are of a maroon color and quite conspic- 

 uous. In most forms, and especially in 

 the dark ones, there is a conspicuous 

 longitudinal white line just above the 

 stigmata or spiracles. This is almost 

 lacking in the entirely grown forms. 

 These two extreme color variants are so 

 different that if observed separately 

 they would not naturally be associated 

 with the same insect, the last form pre- 

 [CoDclnded on paire 73.] 



