18 



,v'»i/'.*.>-y;'*r!^ ■' ' r~ 



The Florists^ Review 



^rt *^T^,i':?, ■!i?.-.w--> ■ ^y7''fl5^-^'f^*^5f:rr>*jR>5P»^^ 



Mat 11, 1916. 



,_ ■ ^ J 



HOW TO FIGHT 

 THE RED SPIDER 



A SCIENTIST'S ADVICE. 



' [The following Is a paper by Parker Thayer 

 Barnes, assistant zoologist of the Pennsylyanla 

 State Department of Agriculture, Harrisburg, 

 Pa., read before the Philadelphia Florista' Club 

 May 2.] 



^he red spider is a pesky pest, with 

 which everyone who grows plants under 

 glass has a tussle sooner or later, usually 

 sooner. It also at times gives much 

 trouble to shade, trees and even to fruit 

 trees. There really seems to be no 

 limit to the extent of its ramifications. 



The red spiders are mites. They be- 

 long to the great class of arachnida, 

 to which spiders, scorpions and the 

 daddy-long-legs belong. They bear to 

 the more highly developed and com- 

 plex insects, such as the moths and 

 flies, a position somewhat similar to 

 that of the ferns to flowering plants, 

 although this is rather a poor simile. 



The red spider is not a new insect 

 in any way one may look at it. New 

 species are being found from time to 

 time, but that is because but few spe- 

 cialists have worked in this branch of 

 the animal kingdom, and they are so 

 much alike that it is really hard to dis- 

 tinguish them. They have four pairs 

 of legs — only three when born, but the 

 other pair develops while they are 

 young. 



Habits of the Bed Spider. 



They winter outside under stones, in 

 leaves and other rubbish, and when 

 warm weather returns, about the time 

 the leaves appear, they climb into the 

 trees and plants and start laying eggs. 

 Each female can lay from five to ten 

 eggs a day for a period of eight to 

 twelve days. In five days they become 

 adults. Brood after brood is produced 

 all summer, unless the weather inter- 

 feres. Much the same conditions exist 

 in the greenhouse, except that the 

 spiders do not hibernate, because it is 

 warm there the year around. 



The mites do not travel fast except 

 when disturbed; ordinarily they move 

 slowly, and for a greater portion of the 

 time they are stationary, sucking the 

 sap from the leaf on which they are 

 resting. The removal of the sap from 

 the cell causes the cell to dry out and 

 die, which gives the leaf that peculiar 

 look always associated with a severe 

 attack. A similar appearance is caused 

 in the fruit trees sometimes by a little 

 leaf hopper. 



By Its Web It is Known. 



The genus of mites that includes the 

 common red spider is tetranychus, and 

 all the members of this genus spin a 

 fine thread. In severe attacks these 

 threads are so abundant as to form a 

 web, either upon the upper or lower 

 surface of the leaves or covering the 

 branch or a number of leaves. I have 

 seen this occur in greenhouses where 

 things were allowed to run in a hap- 

 hazard way. The use of this web no- 

 body seems to understand. It affords 

 no protection to the mites. Dr. Baulea 



suggests that its chief use is to hold 

 the eggs, while another scientist sug- 

 gests that it keeps the eggs from fall- 

 ing off the plant while they are molt- 

 ing. Experiments have proven that it 

 does not in any" way serve to aid their 

 progress. 



The spinning organs that produce 

 this web are supposed to be situated in 

 the spider's head, the threads coming 

 out through the palpi or feelers, but 

 some delicate dissection work under a 

 high-powered microscope still is neces- 

 sary in order to locate the red spider's 

 spinning mill. 



The Greenhouse Species. 



The common species of the green- 

 house is T. bimaculatus. They are sup- 

 posed to be red in color, but anyone 

 who has ever examined them under a 

 hand lens knows that some of them 

 have a washed-out color, much like the 

 crushed strawberry -colored shirt that 

 has gone through the laundry. But the 

 color does not vary in a colony; all of 

 one colony are the same shade of color. 



This species is by no means confined 

 to greenhouses, as I have already inti- 

 mated, nor to our northern climate. It 

 is common in the south, at first on vio- 

 lets, but it now has spread from this 

 humble plant to the cotton plant. On 

 this it works such damage that it has 

 been necessary for the federal bureau 



of entomology to detail men to learn 

 how it can be easily and cheaply com- 

 bated. In California it has threatened 

 the hop crop -and again the government 

 has come to the aid of the beer drinkers 

 and saved the backbone of their staple 

 beverage. From this you can see that 

 the grower of plants under glass is not 

 the only sufferer from the mites or red 

 spiders. 



The orange groves of Florida and 

 California are infested with a couple of 

 species. It was a serious pest as far 

 back as 1889, for the report of the en- 

 tomologist of the United States De- 

 partment of Agriculture of that year 

 said it was a menace to the crop. 



Others of the Tribe. 



A pale greenish species, T, pratensis, 

 is abundant in the west on alfalfa and 

 other crops. A bright red species, T. 

 opuntisB, plays hide-and-seek on the 

 prickly pears of Texas. A short-legged, 

 short-haired European species is found 

 on the spruce trees of Canada. An- 

 other species is common on the leaves 

 of the oak and chestnut, and a com- 

 paratively recent arrival from Europe is 

 T. pilosus, which much prefers the fruit 

 trees of our orchards. The European 

 plum seems to be the favorite food 

 plant of this species. 



The array of species is no doubt 

 uninteresting and to the average person 

 a red spider is a red spider and just 

 as much of a pest as Elias Butler 

 Parker 's guinea pigs of ' * Pigs Is Pigs ' ' 

 fame. 



How are we to get rid of themf That 

 is the question, and I suppose it was 

 upon this point that our friend Watson 

 hung the word explosion — "A Bed 

 Spider Explosion." He thought that 

 maybe I would blast all your precon- 

 ceived ideas about the subject of red 

 spiders. 



(To be Continued.) 





^.'#^.<<^.<<^.^*^.<»^.'»^ i 



TWO LIVELY Mr 

 CLUB MEETINGS 



feV#^''yr#>'-yr»!)''yr»)"'i;'r»^'^;^r»>'4ir»!)'-yr»)'fer»>'fer»)'fer»!)'fer»)'^;fe») •■yr»>'^r» 



CHICAOO CLUB MEETS. 



President Gets Gavel. 



The notable feature of the meeting 

 of the Chicago Florists' Club, May 4, 

 at the Morrison hotel, was the expedi- 

 tion with which it was conducted when 

 once started. The start, however, owing 

 to the dilatory arrival of many of the 

 members, was deferred until the even- 

 ing was fairly well advanced. The at- 

 tendance, though not large, was good 

 considering the fact that there was no 

 fixed program. 



When the usual routine of business 

 was disposed of, a package was handed 

 to President Henderson, together with 

 a letter. Both were from Anton Then. 

 The letter set forth that as every com- 

 mander of an army must have a sword, 

 so every president of a club should have 

 a gavel. And having the utmost faith 

 in Mr. Henderson's abilities and capa- 

 bilities, he took pleasure in sending the 

 accompanying package. This contained 



a most unique and artistic gavel, ingen- 

 iously contrived out of a wild smilax 

 root from Magnolia Springs, Ala. In- 

 scribed on it are the words, "To the 

 president of the Chicago Florists' Club. 

 A strong root will grow to be a strong 

 plant. A. Then." After trying it out, 

 Mr. Henderson passed it around the 

 room for examination. A vote of thanks 

 was given to Mr. Then for the gift. 



Friedman's Show Plan. 



O. J. Friedman took advantage of 

 the opportunity to express himself rela- 

 tive to the annual Easter fiower sale 

 at the Congress hotel for the benefit 

 of the Home for Destitute Crippled 

 Children. He has conferred with Qeorge 

 Marcey, president of the board of direc- 

 tors of the home, and is now in position 

 to state that the directors of the home, 

 as well as the society women who sup- 

 port it, are willing to waive the siue 

 providing the Chicago Florists' Clnb 

 and the Horticultural Society of Chi- 

 cago will cooperate with them during 



