THE GEEENHOUSE THEIPS. 



Fig. 2. — Greenhouse thrips: «, Egg: b, 

 larva, first stage; c, larva, full growTi. 

 All enlarged about 40 diameters. 

 (Author's illustration.) 



These records of occurrences at several locaKties m the Tropical and 

 Lower Austral life zones of tliis country point strongly to tropical 

 America as its original home. This is further strengthened because 

 of its well-known habit of hving in greenhouses, in many locahties, 

 upon exotic plants from the Tro})ics. 

 From this habit it has become widely dis- 

 tributed in Europe and North America. 

 In Europe it is recorded from England, 

 Germany, Austria, Russia, Finland, 

 France, Spain, and Italy. It is also 

 known to occur in Austraha and the 

 Hawaiian Islands. 



In this country it is recorded from 

 Massachusetts, from several places in 

 Michigan, and from Washington, D. C, 

 Florida, and California. It has been col- 

 lected in Iowa and Pennsylvania and in 

 the Barbados and the island of St. Yin- 

 cent, British West Indies. 



Because of the fact that it has been col- 

 lected in such widely distant places in all 

 sections of the country, we can safely say that Heliothrips hsemorrhoidalis 

 is generally distributed in greenhouses throughout the United States. 



NATURE AND EXTENT OF INJURY. 



The damage caused by the greenhouse thrips to ornamental plants 



is confined to the foUage entirely, 

 in so far as the author is aware, for 

 he Ivnows of no recorded injury to 

 the blossoms of the plants norhas he 

 noticed any. The damage to fruits 

 is divided between injury to the 

 foliage and to the fruit itself. In- 

 jury effected by the thrips is due to 

 the method of feeding on the jdants. 

 Both adults and larvse obtain their 

 food by puncturing the epidermis 

 of the leaf or fruit with their sharp 

 mouthparts,^ and after lacerating 

 the tissue they suck out the vege- 

 table matter and plant juices at 

 the point of attack. The insect 

 then attacks the leaf or fruit in a new i)lace, so that in time it becomes 

 full of tiny pale spots where the vegetable matter has been extracted. 



I For structure of mouthparts see " The Pear Thrips," by Dudley Moulton, Bui. (is, I'ait I, Bur. 

 Ent., U. S. Dept. Agr., pp. 2-3, 1907. 



Fig 3 .—Greenhouse thrips: Prepupa on the left 

 and pupa on the right. Enlarged about 40 di- 

 ameters. (Author's illustration.) 



