20 BULLETIN 518, U. S. DEPARTMENT OF AGRICULTURE. 
In order that there may be no confusion on the pa t of the reader 
as to the insects referred to in the tables by their common names, both 
their common and scientific names are listed herewith: - 
Greenhouse iwiite yi yous ae See eam Trialeurodes vaporariorum (Westw.). 
CUEEUS sIMe@ ally: Moe a se T lo eee hs a Pseudococcus citri (Risso). 
Mong-tavled mealy, pugs ee Pseudococcus adonidum (1.). 
Palmivor avocado mealy bags.) 2 asks Pseudococcus nipae (Mask.). 
Greenhouse Orthezias2 see ee Orthezia insignis {Dougl.). 
Hiloridasreds Scales acta iy ae ee se Chrysomphalus ficus (Ashm.) 
TE OEY EES Ca ee ie Sean ca TN Se ee Coccus elongatus (Sign.). 
SOme gO LOW SCale Si cen Na) eee aa Coccus hesperidum (1.). 
1 Bean a0) 12) 0) CIRC Ni oar dir SNe A RR ST UR Cea a Cerataphis latanae (Boisd.). 
FMemispherical) Scalese a os ia dese aap ged Coccus hemispherica (Targ.). 
Hlorida fern caterpillars. eee Hriopus floridensis (Guen.). 
ASDIOUS EE a) SCA Le lee aig a a ae es Hemichionaspis aspidistrae (Sign.). 
Messellated scales fe 2s Oa Ve Ve as EHucalymnatus tessellatus (Sign.). 
AZ ale al VE rIOCOCEU Ss es UN Eriococcus azaleae (Horv.). 
Aalbeai lea Ce wal sss a ite a So Stephanitis azaleae. (Horv.). 
Greenhouse; thrips<2 2202 ee ee _Heliothrips haemorrhoidalis (Bouché). 
DINO MM INTE TO Sees Bale ee nei ae ee Thrips tabaci (Lind.). 
Wottomy scale weg rea a ee eee Pulvinaria sp. 
PBN AGG SCAN et See tle. rd WTS Oe TEE Lee Ischnaspis longirostris (Sign.). 
NVOGAG OS WAT te) My eo ee ea Trialeurodes floridensis (Quaint.). 
IROSevleathopper sli eee dui lea eee Typhlocyba rosae (1.). 
(Ope HSCs Wc a A I a Parlatoria proteus (Curt.). 
CONCLUSION. 
The results indicated in the foregoing pages are for the most 
part based on the fumigation of commercial houses under commercial 
conditions. The slight variations in the percentage of insects killed 
and injury to plants may be accounted for by the tightness or lack 
of tightness of different houses. It is obvious, therefore, that it is 
not practicable to give specific directions as to the amount of cyanid 
to be employed under all conditions. A knowledge of the pests to 
be controlled and of the condition of the plants and tightness of the 
house under consideration will render it possible to determine the 
dosage to be used. 
In fumigating a house containing a large variety of plants, using 
the correct dosage and under proper conditions, it happens occa- 
sionally that some plants appear to have been injured. However, 
this injury is not permanent, as the plants will show new vigorous 
growth in a short time. Repeated tests have demonstrated thor- 
oughly that the growth of many plants is stimulated by hydrocyanic- 
acid gas. 
O 
