2 THE GREENHOUSE THEIPS. 



the anal end of the body, and when tliis becomes too heavy it ch-ops to 

 the leaf surface and dries into a black dot. Where the insects are 

 numerous these exudations produce a marked discoloration of the 

 foliage. Upon becoming full grown the larvae change to the resting 

 stages — prepupa and pupa (see fig. 3) — during which time they 

 remain more or less motionless among the feeding 5'oung and take no 

 food. These stages require periods of about four to six d&js, after 

 which the adults emerge. Figure 5 shows a colony of pupae on a leaf 

 of croton. The total time required for this insect from the time the 



Fig. 1. — Greenhouse thrips {Hdiothrips hxTnonhoidalis): Adult female, enlarged about 50 diam- 

 eters, and greatly enlarged drawing of antenna underneath. (Author's illustration.) 



egg is laid until the adult emerges ready to reproduce its kind is from 

 20 to 33 days, and as this insect continues active in the greenhouse 

 the entire j^ear many generations occur each year. 



ORIGIN AND DISTRIBUTION. 



Although tliis insect was first described from Europe and is there 

 widely distributed, it is without doubt indigenous to tropical 

 America. It has been recorded in the open in St. Vincent and Bar- 

 bados. This insect has been collected at Miami, Fla., on plants in 

 the open in midwdnter. At Santa Barbara, Cal., it caused consid- 

 erable damage to ornamentals in one of the parks in November. 



