4 CIECULAK 3 4 6, U. S. DEPARTMENT OF AGRICULTURE 



more hemispherical than that of the common aphid-feeding beetles 

 of the family, and by the copper-colored back, which bears 16 black 

 spots. 



The majority of the common aphid-feeding species are red and 

 usually bear a variable number of black spots on the wing covers. 

 The convergent lacty beetle (Hippodamia convergens Guer.), illus- 

 trated in figure 1, is probabhy the one most frequentty seen, particu- 

 larly in the Western States. Nearly all species of aphids that do 

 not bear a waxy covering are attacked by this beetle, which often 

 plays an important part in checking aphid infestations. 



The life histories of the beetles of this group are similar, and that 

 of Hippodmiiia convergens is quite typical. The eggs are lemon 

 yellow in color, spindle-shaped, and measure about one-twentieth of 

 an inch in length. They are deposited in compact clusters of from 10 

 to 30 upon the foliage, usually among or near the aphid colonies, 

 and each female may deposit as many as 1,000 eggs. Hatching 

 takes place in about 5 days under summer conditions. The larva 

 then feeds for about 16 days, and during this time 'it may eat from 

 200 to 500 aphids, as it is very active in its search for food. When full 



Figure 1. — The convergent lady beetle (Hippodamia convergens), a feeder on aphids: A, 

 Adult beetle ; B, pupa : C, mature larva ; D, egg cluster. A, B, and C, about 4 times 

 natural size ; D, 8 times natural size. 



grown it has a length of one-half inch. At the end of the feeding 

 period the larva, enters the resting or pupal stage and the compact 

 body remains attached by its tip to the leaf surface or to any other 

 object upon which it may rest. This resting stage covers from 6 to 7 

 days, after which the beetle appears and begins feeding immediately. 

 Each beetle may consume a maximum of about 100 aphids per day 

 during its active adult life. During early summer this may extend 

 over from 1 to 2 months, and the beetles that appear later may sur- 

 vive the winter and resume feeding and egg laying in the spring. 



The overwintering habits of this and related species are of par- 

 ticular interest. At the end of the season the beetles leave the fields 

 and gardens where they have been feeding and migrate to mountain 

 canyons, where they assemble in vast numbers upon low shrubbery 

 and in rubbish; here they pass the winter, usually deeply covered 

 with snow. A single colony, covering only a few square yards, may 

 comprise a bushel or more of the beetles. These overwintering col- 

 onies are most numerous in California, though they are encountered 

 in nearly all of the mountainous sections of the West. 



The influences which bring about this assembling of beetles in 

 such large colonies are not well understood, but it is not induced 

 entirely by the lower temperatures of the fall months, Large col- 



