2 Irtinois NATuRAL History SuRVEY BULLETIN 
As mirids are much easier to handle 
before they have dried out than after, each 
day’s catch was pinned up the following night 
to insure the best possible specimens. All 
mirids were mounted on card points with 
a crimp and in such-a way that the crimp 
Vol, 2277AGiew 
was glued to the side of the mesothorax 
and not to the legs only. The mounted 
specimens were then pinned in Schmidt boxes 
for traveling and taken back to the labora- 
tory at Urbana, where they were labeled 
and later identified. 
Biology 
The eggs of most mirids hatch early in 
the season when the host plants are making 
tender new growth. It is worthy of note 
that in the case of species known to produce 
Fig. 1—Lygus oblineatus, A, egg, front and 
lateral view; B, fifth instar nymph. 
a second generation the host plant is one 
which produces succulent growth during the 
summer season. ‘Thus, the tiny young 
nymphs find the maximum amount of sap 
for food which is essential for plant feeders. 
Mirid eggs, fig. 14, are elongate, slightly 
curved or bean shaped, with a cap and micro- 
pyle on the end pointing to the outside of 
the plant substance where embedded. 
Life Cycle 
Mirid nymphs pass through five instars 
or stages of development and at the fifth 
molt attain sexual maturity and, except in 
special cases where the adults are wingless, 
a set of wings. ‘The time required for 
nymphal development varies with different 
species, but many of them are known to re- 
quire 20 to 30 days. Beginning with the third 
nymphal instar the development of wing 
pads may be observed. During the fourth 
instar the wing pads are clearly evident, 
while in the fifth instar, fig. 1B, the wing 
pads usually extend back to the middle of 
the abdomen. Many mirid species have been 
observed to possess during nymphal develop- 
ment the curious habit or ability of protrud- 
ing a posterior portion of the rectum; when 
a nymph is dislodged and falls from a branch 
cr leaf to the foliage below, the rectum is 
protruded, and, being provided with sticky 
material, acts as an adhesion disk upon strik- 
ing foliage of the limbs below. The nymph 
then scrambles for a foothold, pulls the 
adhesion disk free, retracts the rectum and 
runs for cover among the leaves. Thus the 
eversible rectal disk saves many falling 
nymphs from losing contact with the host 
plant. 
The adult females may mate within 2 or 
3 days after emergence but do not start 
laying eggs until a week or 10 days later. 
The males are generally the first to mature, 
but they do not live so long as the females. 
I have described (1915) in detail the ovi- 
position work ot four mirid species but here 
recount only selected parts. Observations 
on Heterocordylus malinus Reuter were 
made on crabapple and cultivated apple in 
western New York. Females that matured 
June 12 were observed to oviposit on June 
21. On the morning of June 23, four differ- 
ent females were observed while ovipositing. 
When a female is ready to oviposit she 
moves up and down the branch, patting the 
surface with antennae and touching the bark 
here and there with the tip of the proboscis. 
In this manner one spent 6 minutes search- 
ing for a place to oviposit. Another indi- 
vidual required 15 minutes before she found 
a suitable place. The female begins to drill 
the hole by means of the proboscis, and this 
operation may require from 5 to 18 minutes 
before the hole is ready for the insertion of 
