HABITS OF THE ADULT. 21 
and earlier leaves are first attacked in the spring by the adults. 
These feed on the underside of the leaves, scraping out the leaf 
content in small spots that become white and conspicuous. Often 
the adults move along and leave a chain of white spots to mark their 
progress. The adults also feed to some extent on the surface. 
As they feed the females deposit their eggs in the leaf tissues, and 
as soon as incubation is completed the larva? hatch and join the 
adults on the leaves. Under these conditions the leaves become more 
or less dried and lifeless, and the adults move to the higher and more 
tender leaves of the plant. In this way the entire plant may become 
infested. On February 5, 1911, the writer found the adults of this 
insect extremely abundant in the pea field of some Chinese truckers 
at Hollywood, Cal. Here nearly every plant had 7 or 8 adults feed- 
ing on the underside of the foliage, and in many cases 5 and 6 were 
present on each leaf. On August 18 of the same year in the same 
locality plants of spiny wild lettuce (Lactuca scariola) were observed 
that had 50 adults feeding on a single leaf. 
The adults seem to feed on a large variety of plants and have been 
found feeding on all of the plants given under " List of food plants." 
It may be well to state at this point that the presence of adults on a 
plant has not been considered sufficient evidence to class that plant 
as a food plant, but whenever larvae of this insect were taken on a 
plant, this was considered sufficient to rank the plant as a host. 
In the spring when the adults leave hibernation they collect on 
the wild food plants present and feed on them until their injury, 
due to an increase in numbers and feeding, weakens the plants and 
shortens the food supply; then they fly to fresh plants of the same 
hosts or to cultivated crops and fruit trees nearby. Of all the food 
plants observed, the spiny wild lettuce {Lactuca scariola) seems to 
be the most favored. This plant has been found to be infested more 
heavily than any of the other food plants concerned, not excepting 
those of economic importance. 
FLIGHT. 
The present writer in his investigations of the greenhouse thrips * 
never observed that insect to take flight naturally, or even when dis- 
turbed. The adults of Heliothrips fasciatus, on the contrary, take 
flight very readily, and if jarred or disturbed will usually fly or jump. 
This species in taking flight raises the tip of the abdomen quickly, 
and separates the wings. It then rises straight up into the air and 
flies rapidly away in short undulating curves. Indeed, to the un- 
trained eye it appears, in flight, exactly like a small speck of soot 
being blown around by a slight breeze. This power of flight aids 
greatly in the dispersion of this insect during the spring and summer. 
1 Loc. cit. 
