14 



BULLETIN 843, IT. S. DEPARTMENT OF AGRICULTURE. 



Fig. 3. — The five-spotted ladybird 

 (Hippodamia 5-signata) , an 

 enemy of the bean ladybird. 

 Enlarged. 



northern climates. This is not a theory but is based on facts. It is 

 indicated by the fact that many eggs, larva?, and pupse occur so late 

 in the fall that they are killed by freezing. Many larvae starve be- 

 cause the foliage of the bean plants on which they had been feeding 



was destroyed by early fall frosts. It 

 is also not uncommon to find many 

 dead adults in their hibernating quar- 

 ters where they had been killed by 

 winter temperatures. 



NATURAL ENEMIES. 



The insect enemies of the bean lady- 

 bird are, as far as has been learned, not 

 particularly effective in holding it in 

 abeyance. The beetles are well pro- 

 tected by their firm elytra or wing cov- 

 ers and by a repellent yellow liquid 

 which oozes from their knee joints in 

 small drops when the insects are disturbed. This liquid possesses a 

 disagreeable odor and doubtless a similar flavor, which, it is believed, 

 may protect the beetles from the attacks of natural enemies. 



June 27, 1916, two overwintered female beetles were collected at 

 Rocky Ford, Colo., each with the egg of a tachinid fly attached to 

 one of its elytra. One of these beetles 

 died September 4, and the other Sep- 

 tember 9. Fertile eggs were depos- 

 ited at frequent intervals from June 

 29 until September 5, and no 

 parasites developed. This is the only 

 evidence noted of insect parasites. 



Morrill has reported an undeter- 

 mined ant observed eating the eggs 

 on one occasion. 



The adults of three species of pre- 

 dacious ladybirds are known to be 

 natural enemies of this insect. They 

 are : The convergent ladybird 

 {Hippodamia convergens De G.) ; 

 the five-spotted ladybird (Hippo- 

 damia 5-signata Kby., fig. 3), and 

 the transverse-spotted ladybird (CoccineUa transversoguttata Fab., 

 fig. 4). 



These have been reported as destroying the eggs of the bean lady- 

 bird, and next to cold are the most effective known factors in its 

 natural control in Colorado and neighboring States. 



Fig. 4 — 

 bird 

 tat a) : 

 larged. 



-Transverse-spotted lady- 

 ( CoccineUa trans versogut- 

 Adult beetle. Much en- 



