FEBRUARY 22, 1900. 



The Weekly Florists' Review, 



343 



The Buffalo Convention. 



INSECTS INFESTING CARNATIONS. 



By Prof. F. A. Sirrine, ok the New V kk 



.^GRICULTUR-^L E.XPERIMENT ST.ATION. 



Florists in general are not only fa- 

 miliar with all the insects infesting 

 the carnation, but also with the whole 

 category of remedies; hence it appears 

 lilve a waste of time to devote a few 

 minutes to the above subject. Yet, 

 when one can cull from florists' peri- 

 odicals such statements as "Lack of 

 ventilation favors the development of 

 the red spider," or "it resents light al- 

 most as much as fresh air," also "Give 

 as much fresh air as possible — that is 

 what red spider does not like," a few 

 facts regarding the habits and life his- 

 tory of this and other carnation pests 

 will bear consideration. 



Before taking up the subject of hab- 

 its and life history, a portion of an- 

 other statement requires notice. It is: 

 "Water is the remedy for thrlp or red 

 spider. Select some bright morning 

 and syringe heavily and later see that 

 the roots of the plants never get dry, 

 tor drought at some time or other, or 

 too much fire heat, is the source 

 whence both pests originate." Note 

 that the latter portion of this state- 

 ment conveys the idea of spontaneous 

 generation. The days of spontaneous 

 generation, if they ever existed among 

 insects, passed away long before Adam 

 was a gardener. We often hear the 

 expression "A new insect" used. A 

 new creation is not intended by such a' 

 statement. This term is used either 

 when a long established insect adapts 

 itself to new conditions, or it has suc- 

 ceeded up to the present time in keep- 



ing iiul, (if the w;ty i.r a buKoltjgist" 

 with his long label and his still longer 

 name with which he burden.s it. 



The insects infesting carnations inay 

 be separated for convenience into two 

 groups — first, thtjse which are nearly 

 always to be found on the carnation, 

 and, second, those which occur on the 

 plants only occasionally, and then us- 

 ually by accident. That is to say, we 

 have resident and transient insect 

 pests of the carnation. A subdivision 

 of each of the above groups into "forc- 

 nig-house" and "field" pests could eas- 

 ily be made, but all divisions are em- 

 pirical and of value simply to avoid a 

 discusson of each species alone. At 

 this time only the "forcing - house" 

 pests of the carnation will be consid- 

 ered. 



In the first group may be classed the 

 greonfiy, red spider, and thrips; while 

 in the second group we have the cut- 

 worms, cabbage looper (an undeter- 

 mined webworm), the roseleaf tyer 

 the chrysanthemum leaf skeletonizer' 

 Fuller's rose beetle, white grub white 

 ants, and a few others. 



Greenfly. • 



The "greenfly" (rhopalosiphum dian- 

 thi). As the specific name indicates 

 this aphid was first found and de- 

 scribe as infesting dianthus. At pres- 

 ent it might be called polyphagous, as 

 it is known to teed on nearly one hun- 

 dred different varieties of plants. 



This pest is so well known that a 

 description is not needed, but a few 

 words on its habits will not be out of 

 place. Under natural conditions this 

 species of aphid, like most other aphids 

 which feed upon deciduous plants de- 

 posits its eggs late in the fall, in which 

 form it passes the winter, but, under 

 forcing-house conditions this liabit is 

 entirely lost. Instead of the young 

 hatching from eggs, they are produced 

 year after year by a process of internal 

 budding, which we call "agamic re- 

 production." That is, certain cells 

 separate from the abdominal walls of 

 the mother and develop the same as 

 plant buds develop. These buds grow 

 into small aphids and are deposited 

 alive by the parent. No fathers axe 

 needed in this process and they are 

 rarely produced. 



With one exception, as far as known 

 the greenfly never degenerates by be- 

 ing reproduced from buds, like strains 

 of plants degenerate. We have the 

 same kind of propagation in an insect 

 as a florist practices with the variety 

 or strain of a carnation. As most of 

 you are aware, in the case of the 

 greenfly this is not a slow process of 

 reproduction. One mathematician has 

 estimated that the offspring of an in- 

 dividual aphis can in one year amount 

 to 210 raised to the fifteenth power, a 

 number which is almost impossible to 

 express in figures. If there were no 

 checks to this method of reproduction 

 "there would be room in the world for 

 nothing else but aphids," 



I have said that as far as known 

 there is no loss of vitality on the part 

 of the greenfly by the above method of 



