THE PEAR THRIPS. 11 



during the development of the egg and the issuing of the larva it is 

 necessary that the tissue he very flexible; the egg must be in close con-^ 

 nection with the tree sap and must be kept moist, for the egg-covering 

 is elastic and the embryonic thrips within increases in size quite notice- 

 ably before it issues. The egg stage lasts approximately four days. 



As the fully developed eggs are quite large there is space inside of 

 the adult insect's body for but a few at a time — seven or eight. The 

 insect probably places but few eggs during a single day. She feeds for 

 a time and deposits an egg, and then moves to another and still other 

 places; this may be on one or more trees, and thus she spreads her 

 progeny from tree to tree and from place to place wherever she goes. 

 When once set on ovipositing nothing seems to hinder, as we have 

 observed thrips. in the act of placing their eggs at all hours of the day 

 and night and under all conditions of weather. The period of oviposi- 

 tion is of several weeks' duration, or practically all of the life of the adult 

 insect; and when oviposition is finished the life mission of the adult 

 has been fulfilled and death follows. It is interesting to note in this 

 connection that all adult insects which we have observed up to the 

 present time have been females, no males having been found. 



Larva, Description and Habits. — The larvae of the pear thrips, of 

 which we have determined two stages, are tiny, white, soft-bodied, 

 wingless forms, with the customary pair of antennae, three pairs of legs, 

 and with mouth parts similar to those of the adult, as already described. 

 It is interesting to watch, with the aid of a strong lens, a young thrips 

 issuing from the egg. The tiny speck of an incision in the stem of a 

 blossom or leaf tells us where an egg has been placed, and the enlarg- 

 ing of the egg within, causing a swelling in the plant tissue at the 

 summit of which is the incision, tells us of the new insect about ready 

 to emerge. The first signs of life are apparent when the tiny head 

 with its bright red eyes appears, pushing out of the incision; little by 

 little, and, swaying backward and forward, the larva works itself out 

 until about half of the body is exposed, when first the antennte, then 

 one by one the pairs of legs, are made free from their resting position 

 against the body. Still swaying backward and forward, with legs and 

 antennae waving frantically about as if glad of the power of action and 

 eager to get free, the tiny insect works itself out from the egg-covering 

 and the cavity in which the egg was placed, almost to its full length, 

 when it leans forward and eagerly takes hold with its newly formed feet, 

 and with a few final efforts it pulls itself free and walks rapidly away. 

 From'four to ten minutes are required for the young insect to thus free 

 itself from the egg. A number of leaves and blossom-stems in which 

 eggs had been placed were brought into the office and closely watched 

 to determine the length of time spent in the egg. In many cases these 



