308 



WHEAT THRIPS THREE- BANDED THRIPS. 



During their larva state the insects of this order are very 

 nimble, skipping and throwing themselves to a distance by strik- 

 ing their abdomen suddenly against the surface upon which they 

 are placed. In their pupa state they are much more slow and 

 sluggish in their motions, and become quite active again when 

 they reach their perfect state. 



The pupa are like the perfect insects in size and shape, except 

 that their wings are short or rudimentary. At first they are 

 merely oval scales, situated upon each side of the two last 

 segments of the thorax. Subsequently they become more de- 

 veloped so that they reach to the middle of the abdomen or 

 slightly beyond, but they are still incapable of being used for 

 flying. The species under consideration, when in its pupa state, 

 is of the same yellow color as when a larva, but the abdomen, at 

 least towards its base, is paler than the thorax. 



The perfect insect (figure c) is but four hundredths of an inch (0.04) in lengthy 



Its length is indicated by the short line near 

 the left forward leg in the cut. It is thus & 

 fourth smaller than Thrips cerealium, and 

 instead of being black like that species, this 

 retains the yellow color which it has when a 

 larva, the head and thorax (which includes 

 the three large segments next to the head, 

 from each of which a pair of legs arises, as 

 shown in the figure) being of a deep orange 

 yellow, or like the yolk of an egg, whilst the 

 abdomen is paler, and the legs are yellowish 

 white. The antennas (the apical joints of which 

 are represented more enlarged at/) are whi- 

 ' tish, tinged towards their tips with dusky. 

 The fringes of the wings are also dusky. The fore legs are shorter but no thicker 

 than the others. All the other details of its structure are so distinctly represented 

 i n the figure, that a particular description is unnecessary. 



The species which I have noticed as the most common upon 

 wheat in Washington county, New- York, may be named the 

 Three-banded Thrips (Coleothrips trifasciata). It is clearly dis- 

 tinct from the three European species included in this genus, 

 though nearly related to the C.fasciata, Lin. It is nearly double 

 the size of the wheat Thrips, being 0.07 in length, and is so dis- 

 tinctly marked that even our preserved specimens can be readily 

 discriminated. It is of a black color, polished and shining, with 

 the third joint of its antennae white, and its wings black or dark 



