CHAPTER VII. 



Order IV. PHYSOPODA.* 



(Thrips.) 



The members of this order have four wings ; these are similar in 

 form, long, narrow, membranous, not folded, with but few or no 

 veins, and only rarely with cross-veins ; they are fringed with long 

 hairs ; and are laid horizontally along the back when at rest. The 

 metamorphosis is incomplete. The mouth-parts are probably used 

 chiefly for sucking; they are intermediate in form between those of 

 the sucking and those of the biting insects ; the mandibles are bristle- 

 like ; the maxilla are triangular, flat, and furnished with palpi ; and 

 the labial palpi are also present. The tarsi are two-jointed, bladder- 

 like at tip, and without claws. 



These are insects of minute size, rarely exceeding 2 mm. or 3 mrn. 

 in length. They can, however, be obtained easily from various 

 flowers, especially those of the daisy and clover. Ordinarily, it is 

 only necessary to pull apart one of these flowers to find several 

 specimens of Thrips. They are in many cases very active insects, 

 leaping or taking flight with great agility. In case they do not leap 

 or take flight when alarmed, they are apt to 

 run about and at the same time turn up the 

 end of the abdomen in a threatening manner, 

 as if to sting. In this respect they resemble 

 the Rove-beetles. 



The body is long (Fig. ill). The head 

 is narrower than the thorax, without any dis- 

 tinct neck ; the eyes are large, with conspic- 

 uous ocelli ; there are also usually three 

 simple eyes. The ventral side of the head is Fio ^ l _ 



prolonged into a conical beak, which extends be- 

 neath the prosternum. The form of the mouth-parts can only be 

 made out by dissection and the use of high powers of the micro- 

 scope. Fig. 112 represents the mouth-parts of one of our common 



* Physopoda : physao (<f>v craoj), to blow up; pous (itovS), a foot. 



