TWENTY-EIGHTH FRUIT-GROWERS* CONVENTION. 



101 



Hemiptera and we may know them as Thysanoptera. The order is well 

 named Thysanoptera, as it means tassel-winged, which name, from the 

 insects' fringed wings, is peculiarly appropriate. As we have seen, their 

 wings are different from those of any other insect. We have also noted 

 their peculiar mouth, which is structurally mandibulate, though func- 

 tionally it is suctatorial. Thus they are on the fence, as it were, 

 between two great groups of insects: those with typical mouth parts, 

 fitted for biting; and those modified to adapt them for sucking. These 

 two groups contain practically all insects except these Thysanopterons. 

 Once more, all other insects either pass through complete metamor- 

 phosis from egg to adult where the larva, pupa, and imago are all 

 totally unlike and the pupa inactive, or else incomplete, where the three 

 stages are much alike, except for absence or partial development of 

 wings, differences of development in reproductive organs, and in size. 

 In this group the pupa? are always active. These eat ravenously, and 

 are like the larvse, except that they have stubs of wings, and are larger, 

 and also like the adults or imago, except that they do not have fully- 

 developed wings. Here again the thrips is a sort of go-between; it is in 

 appearance like the bug and locust, incomplete in its transformations, 

 yet it is inactive like the pupa of the other groups. For every reason, 

 then, we do well to separate these lilliputs, and, few as they are — scarce 

 fifty are known in our whole country — place them in an order by them- 

 selves — the Thysanoptera. 



Habits of Thrips. — Without doubt most thrips are plant-eaters. 

 Some of our best authorities have pronounced some as predaceous on 

 other insects. Except that some of these scientists are very careful and 

 usually accurate, we would be tempted to think them mistaken and 

 wonder if all thrips were now plant-destroyers. These insects are so 

 small that a mistake would not be strange or unvenial. 



It has long been known that one of the most common thrips, Euthrips 

 tritici, works on grasses, causing the well-known silver top. They have 

 also been discovered as serious enemies of the onion. Except for their 

 minute size, equal mischief might very likely have been discovered in 

 other lines. I have no doubt that their mischief is far more than is 

 known, and so is very inadequately appreciated. 



Natural Enemies. — As each female thrips lays from fifty to seventy-five 

 eggs, we are certain that, numerous as they are, they must have 

 innumerable enemies. These are both animal and vegetable. Insects 

 are the chief of the first and fungi of the second. Some of the Cocci- 

 nellidse — ladybird beetles — especially species of Megilla and Scymnus, 

 prey upon them and doubtless kill great numbers. The little Scymni 

 also destroy the red mite which has become so formidable a pest in our 

 citrus groves. The green lace-winged fly, or Chrysopa, also destroys 

 many of the thrips. The Syrphus fly larva, which is so hungry for plant 



