THE PEAR THRIPS. 15 
Lind.). Both the thrips and the mite were very common in large onion 
fields, covering several hundred acres. A mite would be seen to ap- 
proach and grasp a thrips with its front pair of legs and, inserting its 
proboscis, suck out the body juices of its prey. A single mite was 
often observed thus to kill several thrips within a very few minutes. 
The writer strongly suspects that some mite preys on the younger 
stages of the pear thrips while it is in the ground. This would be 
entirely possible, and mites are commonly found in the grass and in 
the ground. 
A fungus, presumably parasitic, has been endemic among thrips 
during the seasons 1905 and 1906. In its different stages it lives 
on both young and mature thrips, and in a way parallels the life of its 
host. During the spring of 1905 thrips larve were often observed to 
be thickly infesting a tree, and after these had disappeared, presum- 
ably having gone into the ground, none or but few living ones could 
be found. Many larve, too, seemed to 
leave the tree before they ha reached 
full growth, and within breeding cages 
these larve were seen to die as the 
direct result of the parasite. Project- 
ing from their bodies were to be seen 
the tiny fruiting conidiophores of the 
fungus. Adult thrips were seen to be 
attacked by another form of the para- 
site during the spring of 1906. The 
past two seasons have offered almost 
ideal conditions for the development 
of the fungus, enabling it to become 
quite widespread. Fic. 8.—a, Resting spores of a fungus 
The life history of the fungus has found within dead thrips larva, much 
been determined only in part. The at oe ae 
heavy-walled resting spores, the dor- 
mant stage, are found within larve and adults in the ground; never, 
thus far, in pup in the ground or in individuals on the tree. Dead 
larve from the ground show that the internal body organs have all 
been displaced by the fungus, and in most cases the body contains 
only a mass of the heavy-walled spores. The transition which takes 
place in the formation of these spores is as yet not clear, but there 
seems to be a general breaking up of the fungus hyphx within the 
thrips’ body. In one well-prepared specimen there was an indistinct 
grouping of particles around many centers. These were presumably 
the forming spores, for in the next stage the formation of such spores 
was complete. These heavy-walled spores may be found nearly the 
whole year through, although they are especially abundant from May 
until the following February. 
