NO. l8 SENSE ORGANS OF COLEOPTERA — McINDOO 7 



(23) in California is also reconiniended to future investigators. He 

 used large electric lights in an orchard to attract codling moths. 



Gourdon (20) states that ultra-vi(jlet rays have heen found to 

 attract hoth diurnal and nocturnal insects. The rays appear to pro- 

 duce in the insects a sensation which is at first agreeable, but which 

 soon becomes dangerous, if not fatal ; in certain cases they are im- 

 mediately l)linded. A trap for use in vineyards, orchards, or fields is 

 described, to which insects are attracted by means of ultra-violet rays, 

 and are either drawn by the suction of an electric fan into a metal 

 basket or fall blinded outside the trap, where they become an easy 

 prey to birds. 



Many more references on light traps are cited in " The Review of 

 Applied Entomology, Series A," but perhaps enough has been said 

 to convince the reader that this method of control is worth further 

 investigation. 



2. ORIGINAL WORK ON MEXICAN BEAN BEETLE 

 (a) responses of larvae and adults to daylight 



When the sun is shining brightly on warm days, larvae and adult 

 bean beetles are rarely seen exposed to the direct sunshine in bean 

 patches. During cloudy days and early in the morning many may be 

 seen on the upper surface of the leaves, but most of them at all times 

 live and feed on the under surface. 



When brought into the laboratory most of them move toward the 

 windows, being photopositive, while occasionally one moves away from 

 the light, thus being photonegative. When tested in a phototactic box, 

 18 inches long, 12 inches wide, 12 inches high, and lined with a dead- 

 black cloth (fig. i), their responses were similar to those of codling- 

 moth larvae, recently described by the writer (47, i)p. 12-13). This 

 box lay on a table by a south window in bright light, although not in 

 direct sunshine. Dozens of insects were placed in it and the tracks 

 of most of them were traced with a lead pencil. Larvae of the first 

 and second instars were found to be weakly |)hotopositive or indilTer- 

 ent to light. Many moved slowly, bending to the right and left, in 

 any direction as if searching for food, while a few moved in circles 

 toward the light (fig. i, a and b). 



Most of the larvae of the third instar were strongly photopositive 

 (fig. I, r), while the remainder were weakly photopositive or in- 

 different to light. The more active larvae of the fourth instar were 

 usually strongly photopositive, but a few were indifl:'erent. The less 

 active ones were usually strongly photonegative (fig. i, r/). It was 



