58 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
THE LARVA. 
The thrips larva (fig. 15) is white, with red eyes; it moves about 
slowly and does not jump, and, being without wings, it can not fly. 
It does not spin a web, but seeks a sheltered place between rolled or 
folded leaves or in blossoms, or it lies close along the veins on some 
of the larger leaves. It reaches full growth after two or three weeks, 
drops to the ground, and penetrates into it for several inches, where 
it incloses itself in a tiny cell and here remains during all the rest of 
the year. 
Larve do not walk down the larger branches or tree trunks to get 
to the ground, but drop down or are carried 
within the old falling calices, or are more 
usually thrown down by winds or rains. It 
has been observed that a very large percent- 
age of the thrips which are thus thrown from 
the tree are not fully grown. Only those 
which are mature are able to penetrate the 
ground and form their cells; the others die. 
Larve are scattered everywhere under the 
trees, and if the trees are large and have inter- 
mingling branches the thrips are distributed 
over nearly the whole surface of the soil. 
The period during which larve are entering 
the ground begins about April 1, and is at its 
maximum from about April 10 to 30, practi- 
cally all thrips having entered by May 15. 
This period of entermg the ground by larve 
in Contra Costa County corresponds very 
closely to the San Jose record as given above. 
It may be a few days earlier in the warmer 
sections at Suisun, in the Vaca Valley, and 
Fic. 15.—The pear thrips: Larva. along the Sacramento River. 
Muchenlarged. (Author’sillus- = Tarvee penetrate the loose top soil and 
iE usually remain in the 3 or 4 inches of harder 
ground i ee below the surface. They penetrate to a 
much greater depth where the soil is loose, owing to shallow 
spring cultivation, than where it is firmer. If the thrips are 
disturbed during their first few weeks in the ground—for example, 
by cultivation—and if not killed, they immediately go deeper and 
make new cells. The larve remain in a dormant condition, in 
which no food is taken, and do not move from their cells, unless 
