9i8 



The Colorado Beetle. 



[FEB., 



to two feet or more, though eight to ten inches is the average. 

 Exceptionally the beetles pass the winter among rubbish. 



Genial weather in spring brings the beetles from their 

 winter quarters. The beetles fly well and readily, especially 

 during the warmer parts of the day. "In flight the striped 

 elytra (wingcases) are raised and held motionless from the 

 thorax, while the gauzy wings, unfolded and vibrating, strike 

 pleasantly on the eye as the sun intensifies their rosy hues."* 



The females lay their eggs in clusters of nine to forty or 

 more on the under surface of the leaves, attaching them by 

 one end. The eggs may hatch in- less than a week, or they 

 make take over a week, according to the conditions. Chitten- 

 den says that the larvae take from sixteen days to three weeks 

 to attain maturity. When full-fed the larva leaves the plant 

 and passes into the soil, where pupation takes place in a 

 cell. The pupation stage in the most favourable conditions 

 may be over in a week. Thus, where the environment is very 

 favourable, the whole life-cycle can be completed in a month. 

 From some parts of the United States two generations are 

 recorded as occurring in a year, and from other parts three 

 generations. When the weather begins to turn cold in the 

 autumn, the beetles bury themselves in the earth for 

 hibernation. 



Natural Enemies. — A great number of natural enemies tend 

 to check the Colorado beetle in America. Among these are 

 birds which feed upon both larvae and adults, especially the 

 rose-breasted grosbeak (Guiraca ludoviciana) . Both ducks 

 and chickens, but especially the former, devour the larvae. In 

 America the toad (Bufo Americana) gorges itself with the 

 grubs, and our British species would probably also greedily 

 devour them. 



The insect enemies recorded by Riley are very numerous. 

 They are chiefly predatory beetles and blood-sucking bugs or 

 Hemiptera-heteroptera. Strange to say, no members of the 

 Hymenoptera, the order that contains so many parasites, are 

 actually parasitic on the Colorado beetle ; a single species of 

 wasp (Polistes ruhiginosus), however, occasionally provisions 

 its nest with the larvae. A Tachinid fly is parasitic on the 

 grubs. 



* Girault and Rosenfelcl, quoted by Chittenden. 



