2G B.C. Entomological Society. 



Greenhouse Theips. 



The first pests I will deal with are greenhouse thrips. The best description I 

 can give is that taken from Bulletin, Volume 11, Kos. 1 and 2, of the " Monthly 

 Bulletin of Injurious and Beneficial Insects of California," by E. O. Essig, which is 

 as follows : — . ■ ' ' 



Genet al Appearance. — The adult insect is characterized by having the autenuse 

 eight-segmented and twice as long as the head, while the surface of the body Is 

 distinctly reticulated. The abdomen is yellowish-brown, with head and thorax dark 

 brown, and antenun", legs, and wings colourless. 



Life-history. — The very minute, bean-shaped, colourless eggs are inserted iu the 

 leaf-tissues of food-plants, usually on the under-side. They hatch in about ten da.vs. 

 Each female la.vs from ten to twenty eggs. The first hatched larvre are colourless, 

 with seven-segmented antenna?. As they age they become darker in colour and the 

 antennre become eight-articulated. The larval and pupal stages occupy from four 

 to six weeks. All stages feed throughout their life-cycles. There are continuous 

 and overlapping generations, estimated by H. M. Russell to be twelve a year. 



Food-plants. — Food-plants are, with very few exceptions, all plants grown in 

 greenhouses. My reason for dealing with Thrips first and giving them the most 

 prominent place in this paper is -because I consider that they do as much, if not 

 more, damage than all the other pests combined, and are by far the hardest to 

 control around Victoria District, but they cause most loss in carnations. 



The grower may not suspect their presence until one-third, or I have known 

 one-half of his crop ruined b.v this pest. The first indication he will notice of the 

 presence of Thrips will be that the edge of the petals of the blossom is discoloured, 

 having a dried or burnt appearance on the light-coloured flowers, and the red and 

 crimson ones will have white spots on them. Now, by carefully pulling the flowers 

 apart, there will be found from one to a dozen of these pests working very 

 industriously. 



Control. — This is a very difficult matter, as I am satisfied that Thrips work very 

 little among the carnation-foliage, but lay their eggs and are hatched out in the 

 bud of the carnation, and during this time they are almost hermetically sealed in 

 the tight folds of the carnation-bud, so I consider spraying of very little value; at 

 least, that is what I have found. I have tried heavy fumigating with red pepper 

 and tobacco-stems to be of considerable value, but the best remedy, at least the one 

 we have most success with, is fumigating with nico-fume, or Black Leaf 40. This 

 is best applied by painting the return pipes and turning on the steam ; as soon as 

 this has been done, taking care that all ventilators are tightly closed. If the grower 

 does not heat by steam, he can get the same results from hot water, pi-oviding he 

 can heat the pipes to a temperature of not less than 190° Fahr., and more, if possible. 

 Failing this method, the next best way is to vaporize the nicotine solution over a 

 spirit or coal-oil lamp. The quantity of nicotine solution to use depends on the size 

 of the house to be fumigated, but full directions are given on the tins containing 

 these solutions, and I have found these directions very satisfactory. 



By keeping the temperature of the houses in as moist a condition as can be done 

 with safety, and by frequent syringing, it will have a strong tendency to keep these 

 pests in check, as they do not like moisture. This can be done with comparative 

 safety during the months of Jul}-, August, September, and the first two weeks in 

 October in this district, these being the months in which the most damage is done 

 by Thrips ; after this time they practically disappear until the following season. 

 A great help is to keep the greenhouse perfectly clean, allowing no rubbish, dead 

 flowers, etc., to he around on the paths or on and under the benches. 



Some growers use % to % oz. of potassium cyanide and 3 oz. of sulphuric acid, 

 C.P., dissolved in 4 oz. of water ; but, personally, I do not like this method, as it is 

 dangerous unless very carefully handled, and the results are sometimes very dis- 

 astrous to the plants. I have found when using cyanide that one time you get 



