344 



I'he Weekly Florists^ Review* 



FEBRUARY 22, 1900. 



reproduction. At times the older speci- 

 mens, whicli usually live only about 

 three weeks, become inert and repro- 

 duce very slowly. Whether this is due 

 to exhaustion or is a provision to carry 

 them through unfavorable conditions 

 is not known. Possilily it is a form of 

 hibernation. This much is certain: 

 tobacco smoke will not kill the.se indi- 

 viduals and they will stand hydro- 

 cyanic acid gas better than will the 

 plants. Conditions which bring about 

 this inert state are, exhaustion of the 

 plant on which they are feeding, and 

 frequent fumigation of the plants with 

 tobacco smoke. 



Not all the individuals of each brood 

 develop wings, but under forcing house 

 conditions winged females are pro- 

 duced in nearly every brood. This is 

 necessary to prevent overstocking a 

 plant. It also allows them to spread to 

 all parts of the house more rapidly. 



Red Spider. 



Red Spider (Tetranychus telarius). 

 Here we have another pest which 

 needs no description, as it is already 

 well known by all. The red spider dif- 

 fers slightly from the gi-eenfly in its 

 method of reproduction. Bach brood 

 hatches from eggs which are deposited 

 on nearly all kinds of plants during 

 every season of the year except winter, 

 but, as with the greenfly, males are not 

 always needed. The red spider be- 

 longs with the true mites, such as 

 sugar and cheese mites, itch mites, etc. 

 At the same time the mites form one 

 branch of the spider family. The red 

 spider spins webs, the same as all 

 spiders, which are of special use in 

 fastening the eggs to the leaf. 



Judging from the clipping previous- 

 ly quoted, which claimed that the red 

 spider originated from too much fire 

 heat or drought, the life history of this 

 pest is not all known. Under natural 



conditions, at this season of the year, 

 they are to be found on plants in the 

 egg stage only. Their eggs can be dis- 

 covered at the present time on many 

 plants, both annual and perennial, liv- 

 ing and dead, looking like mere red 

 dots. The parent spider deposits these 

 eggs in the fall, around the bud.-;, un- 

 der rough bits of bark, and even on 

 the leaves which drop. During the lat- 

 ter part of April I have seen newly 

 hatched young swarming over the 

 grass under chestnut trees and travel- 

 ing up the body of the tree in such 

 countless numbers that the bark ap- 

 peared to be in motion. 



Ten days to two weeks are required 

 before the first brood is developed 

 enough to commence to lay eggs. After 

 this period tliere is a new brood about 

 once in every three weeks throughout 

 the whole season. They thrive and in- 

 crease rapidly wliile there is plenty of 

 wind and bright sunlight. Excessive 

 rains in May and June do not injure 

 the eggs, but they have" a l>ad effect on 

 the young or newly hatched red spi- 

 ders. They appear to get tangled in 

 the wet webs and are not able to sur- 

 vive the chill which they receive. Dur- 

 ing extreme heat of midsummer the 

 egg laying is sometimes checked, but 

 usually they can stand plenty of heat 

 combined with sunlight and air. 

 Hence you see that naturally this in- 

 sect thrives under conditions which 

 are supposed by some to be adverse to 

 them, especially in forcing-houses. 



I have yet to see it proven that 

 syringing plants with water has any 

 effect on the adult insect. A few of 

 them may be knocked from the plants 

 by the force of the water, but they 

 soon crawl back. I have observed that 

 the best time to have apparent suc- 

 cess with syringing of plants with 

 water is to wait until a good many 

 eggs are deposited, then apply the 

 water with force. The old exhausted 



red spiders are knocked from the 

 plants and the result is that the plants 

 will appear clean for a week or ten 

 days — that is, until time for the new 

 brood to hatch from the eggs. 



The immature red spider can be 

 distinguished from the adult by the 

 fact that they only have three pairs 

 of legs, while the adult has four pairs. 



It is not known how many distinct 

 broods of the red spider occur out of 

 doors each year. In October, when the 

 leaves commence to fall, males occur 

 in the brood and the winter eggs are 

 deposited. It is not known how often 

 males occur under forcing house con- 

 ditions. Their rate of increase is 

 equal to that of the green fly. 



Thrips. 



THRIPS. Several species of this 

 pest occur in greenhouses and attack 

 nearly all kinds of plants. The spe- 

 cies which causes the injury, usually 

 found on "twittered" carnations, has 

 been described as an "Onion Thrips," 

 "Cabbage Thrips." and a "Tobacco 

 Thrips." In the vicinity of New York 

 city carnations are usually infested 

 with this species. Before it was no- 

 ticed injuring onions and cabbage in. 

 this country it was called Thrips to- 

 baci by an European entomologist. 



As this pest and its work are not 

 well known, a full description will be 

 admissible. Furthermore, from recom- 

 mendations given in the Florists' Ex- 

 change for 1S9S, p. 1124a, quoted from 

 Peter Hendersons "Practical Floricul- 

 ture," this pest has apparently been 

 confused with the so-called "rose- 

 thrips." which is not a thrip at all, but 

 a leaf-hopper, one of the Jassidae. 



The adult insects are winged and 

 have six legs. Their wings, of which 

 there are two pairs, are very thin, 

 delicate membranes, fringed with long 

 hairs. They are not able to hop, but 



General View of the Carnation Society's Exhibition at Buffalo last Thursday and Friday. 



