I04 



INSECTS 



early spring favor the plant lice they increase until 

 June, when the first hot, dry spell puts a period to their 

 work. An unusually cold, wet spring will be accom- 

 panied by an unusual abundance of lice, and on three 

 occasions within twenty years when the cold, wet 

 weather extended into late Jvme, infestation became 

 so serious that the leaves were covered with honey- 

 dew and soot-fungus, so that they choked and began 

 to drop. But about this 

 time the ladybirds were 

 also in the running and 

 had become so numerous 

 that they were fast reduc- 

 ing the plant lice and put- 

 ting a period to the infes- 

 tation. And then came the 

 long deferred hot spell in 

 early July, wiping out the 

 plant lice as with a sponge 

 and leaving thousands of 

 beetle larvae without food. 

 What did they do? First 

 the larvae ate all the eggs 

 of their own kind yet on the leaves; then they ate the 

 helpless pupae getting ready to change to the adult stage ; 

 then the large larvae ate the smaller ones and as they 

 became full fed and pupated, they in turn became vic- 

 tims to those that had escaped the slaughter. And before 

 the end of July the 15 -spotted ladybird beetle was again 

 a rare insect and no outward sign remained to tell what 

 crowds of them had been on the scene a month before. 

 But not all Coccinellids are able to increase so 

 rapidly ; some species being strictly limited to one 

 brood. The cottony maple scale in the east is con- 

 trolled by the signate ladybird. Hyper as pis signata, 



^IG. 47. — 15-spotted lady-beetle: ( 

 larva; b, pupa; d-g, adult varieties. 



