182 THYSANOPTERA AND ORTHOPTERA. 



venting distortion. Carnoy's solution was used in the field, though I 

 have employed others at different times. Final preservation was in 

 95% alcohol. Distortions were not wholly prevented, however, the 

 insect being in nearly every case somewhat longer and more slender 

 than in life. 



ECOLOGY OF THE THYSANOPTERA. 



Scheme of Classification. 



It has been found impracticable to classify Thysanoptera according 

 to the ecological schemes in use for this and many other groups. Jordan 

 (1888, p. 603) divided Thj^sanoptera into three classes according to 

 the food. The first was the flower-inhabiting class ; the second included 

 those which live on the under side of leaves; the third was made to 

 comprise all other forms, such as those living on roots, under bark, on 

 lichens, on fungi, under wet or dry leaves, or under decaying plant 

 matter. This last category is too inclusive to be satisfactory from an 

 ecological point of view. 



The same species (Eidhrips tritici) may be found on Kentucky blue 

 grass {Poa pratensis) which grows in dry to moderately moist open 

 situations everywhere; on Canada thistle (Cirsium arvense) and dog- 

 fennel {Anthemis cotula) growing along roadsides; on the beach-pea 

 {Lathyrus maritimus) and Pitcher's thistle (Cirsium pitcheri) which 

 grow on sandy beaches; on the swamp rose {Rosa Carolina) and cinque- 

 foil (Potentilla fniticosa) growing in half-dry marshes; on heal-all (Pru- 

 nella vulgaris) and woodland sunflower (Helianthus divaricatus) in open 

 woods; on the button-bush (Cephalanthus occidentalis) and swamp 

 milkweed (Asclepias incarnata) standing at the edges of ponds; and on 

 pickerel weed (Pontederia cordata) which grows in shallow water some- 

 times far from the nearest land. It is therefore impossible to classify 

 species of Thysanoptera as campestrian or sylvan, xerophile or hygro- 

 phile, as Morse (1904, p. 14) has proposed for Orthoptera. A glance 

 at the list of plants infested by a single species makes it evident, further- 

 more, that thrips in general cannot be grouped according to their food 

 plants. The same species sometimes feeds on plants of widely different 

 orders. This is especially true of certain members of the suborder 

 Terebrantia, of which Euthrips tritici (p. 208) sind Thrips tabaci (p. 211) 

 are the most common representatives in Huron County. The sub- 

 order Tubulifera is somewhat less general in food habits, but even 

 among some of these the few plants inhabited by one species belong 

 to very different groups. 



The nature of the place inhabitated by species, however, is usually 

 rather definite and characteristic of that species. An inspection of the 

 habitats given in the annotated hst of species (p. 207 et seq) will make 



