WHEAT THRIPS EUROPEAN GRAIN THRIPS. 305 



minute objects can be satisfactorily studied, and described with 

 that precision and fullness which science requires. 



Insects of the kind to which these belong may be distinguished 

 from all others by their wings (see the accompanying figure, e), 

 which are long, narrow and strap-like, and in most of the species 

 are fringed on both sides with long hairs like eye-lashes. Their 

 mouths are also different from those of all other insects, being 

 nearly intermediate between the beak or bill with which some of 

 the orders of insects puncture and suck the fluids on which they 

 subsist, and the jaws with which all the other orders gnaw the sub- 

 stances on which they feed. These insects originally formed the 

 genus Thrips, placed by Linnaeus next to the plant-lice, in the 

 Order Hemiptera. But as their wings and the structure of their 

 mouths is so wholly unlike that of any other insect, naturalists 

 of late rank them as a distinct order, which is named Thysan- 

 optera, i. e. fringe- winged. This order contains the single 

 family Thripidid^: (currently written Thripidae by authors, but 

 incorrectly), which is divided into seven genera by Mr. Haliday, 

 whose researches in this group have been unsurpassed. About 

 fifty species of these insects are known to the entomologists of 

 Europe. They are all of small size, more than half of them 

 being only about the twentieth of an inch in length, or less, and 

 but few slightly exceed the tenth of an inch; though recently 

 some have been found in Australia which are three times as large 

 as any which were previously known. 



Most of the species are found in the flowers of different plants. 

 They feed upon the juices, and are very injurious, especially in 

 hot-houses, causing small dead spots upon the leaves and flowers 

 wherever they wound them. Some of them also infest melons 

 and cucumbers. One species is very injurious to the olive trees 

 in Italy. Another attacks peaches and other fruit to a mis- 

 chievous extent. But the species which appears to do the 

 greatest amount of damage is the grain Thrips (T. cerealivm). 

 Our first accounts of this insect are from Mr. Kirby, in 1796 

 (Linnaen Transactions, iii, 246), who however supposed it to be 

 the Thrips physapus of Linnaeus, until Mr. Haliday showed it to 

 be distinct from that species. An excellent history of this 



[Assembly, No. 21 5. J 20 



