INSECTS AFFECTING PARK AND WOODLAND TREES 4II 



creep beneath the surface of the pitch and rapidly grow to twice their 

 original size, gradually making their way toward the portion of the twig 

 from which the pitch is exuding. This results in their collecting in a 

 group with their mouths close together and their bodies extending toward 

 the surface of the mass. The very young larvae have hooklike spines on 

 the ventral surface of each segment. These disappear with growth, and 

 the entire skin becomes covered with fine, backward curving spines. After 

 15 or 18 days the young attained a length of from to about ^ inch. 

 Miss Eckel's observations demonstrate that the parent insects take 

 advantage of normal exudations of resin on which to oviposit, and that the 

 flow of this substance may be increased to some extent by the larvae 

 rasping the living tissues. This latter is particularly liable to occur when 

 the supply is somewhat deficient. 



Adults have been bred by us during the latter part of June and in 

 early October. They were also reared from material collected which was 

 supposed to represent only the work of the pine twig moth, E v e t r i a 

 comstockiana Fern. It is not improbable that a few eggs may be 

 deposited in pitch masses around the galleries of this borer and the larvae 

 come to maturity under such conditions. The normal pitch mass inhabited 

 by this little fly, may contain from two to about 30 larvae which, when full 

 grown, measure about ^ inch in length. They are a pale orange while 

 feeding, and on the approach of maturity become a bright orange color. 

 The larvae are elongated, widest about the middle, and the underside of 

 segments 1 to 7 are each provided with two transverse rows of black or 

 brown spines which probably aid in locomotion. Professor Comstock 

 states that while they burrow in the bark and resin, the anal tubercles are 

 always at the surface, thus permitting the insect to breathe, and when the 

 larva contracts to a pupa, the end of the body is drawn in, though an open 

 channel is left for the passage of air. The pupa works its way partly out 

 of the pitch mass before disclosing the little midge, which has a wing 

 expanse of about \^ inch, the thorax gray and the abdomen in living 

 specimens, a dark red. 



